Patent Publication Number: US-2021175042-A1

Title: Integrated device having gdt and mov functionalities

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of International Application No. PCT/US2019/049008 filed Aug. 30, 2019, entitled INTEGRATED DEVICE HAVING GDT AND MOV FUNCTIONALITIES, which claims priority to and the benefit of the filing date of U.S. Provisional Application No. 62/726,094 filed Aug. 31, 2018, entitled INTEGRATED DEVICE HAVING GDT AND MOV FUNCTIONALITIES, the benefits of the filing dates of which are hereby claimed and the disclosures of which are hereby expressly incorporated by reference herein in their entirety. 
    
    
     BACKGROUND 
     Field 
     The present disclosure relates to an integrated device having gas discharge tube (GDT) and metal oxide varistor (MOV) functionalities. 
     Description of the Related Art 
     A gas discharge tube (GDT) is a device having a gas between two electrodes in a sealed chamber. When a triggering condition such as a high voltage spike arises between the electrodes, the gas ionizes and conducts electricity between the electrodes. 
     A metal oxide varistor (MOV) includes a metal oxide material, such as zinc oxide, implemented between two electrodes. Under normal condition (e.g., at or below a rated voltage between the electrodes), the MOV is non-conducting, but becomes conducting when the voltage exceeds the rated voltage. 
     SUMMARY 
     In some implementations, the present disclosure relates to an electrical device that includes a first layer and a second layer joined with an interface, with each having an outer surface and an inner surface, such that the inner surfaces of the first and second layers define a sealed chamber therebetween. The electrical device further includes an outer electrode implemented on the outer surface of each of the first and second layers, and an inner electrode implemented on the inner surface of each of the first and second layers. The first layer includes a metal oxide material such that the first outer electrode, the first layer, and the first inner electrode provide a metal oxide varistor (MOV) functionality, and the first inner electrode, the second inner electrode, and the sealed chamber provide a gas discharge tube (GDT) functionality. 
     In some embodiments, the electrical device can provide a functionality of at least one GDT and at least one MOV connected in series. For example, the at least one GDT can include one GDT and the at least one MOV can include one MOV. The electrical device can further include an electrical connection between the second inner electrode and the second outer electrode, such that the first inner electrode, the sealed chamber, and the second electrode electrically connected to the second outer electrode form the one GDT with the second outer electrode providing an external terminal functionality. The second layer can include an electrically insulating material such as a ceramic material. 
     In another example, the at least one GDT can include one GDT and the at least one MOV can include a first MOV and a second MOV, with the one GDT being between the first and second MOVs, and the first MOV being associated with the first layer. The second layer can include a metal oxide material such that the second inner electrode, the second layer, and the second outer layer form the second MOV. At least a portion of the interface can include an electrically insulating portion such that the first layer and the second layer are electrically insulated. The electrically insulating portion of the interface can include a sealing layer implemented between the first and second layers. The sealing layer can include, for example, a glass sealing layer. 
     In some embodiments, the electrical device can further include an emissive coating formed over each inner electrode of the first and second layers. 
     In some embodiments, each of the first and second layers can define a pocket on the inner surface, such that a perimeter of the inner surface is raised relative to a floor of the pocket. The respective inner electrode can be implemented on the floor of the pocket of each of the first and second layers. 
     In some embodiments, the interface can include a spacer layer implemented between the first and second layers, and along a perimeter of the first and second layers. The spacer layer can be formed from an electrically insulating material such as a ceramic material. 
     In some embodiments, the electrical device can further include a first sealing layer implemented between the first layer and the spacer layer, and a second sealing layer implemented between the spacer layer and the second layer. 
     In some embodiments, each of the first and second layers can be substantially flat, and the first and second layers can define a side wall. In some embodiments, the spacer layer can include an outer lateral edge that is substantially flush with the side wall. In some embodiments, the spacer layer can include an outer lateral edge that extends laterally outward beyond the side wall. 
     In some embodiments, the first layer can be an approximate mirror image of the second layer about a mid-plane between the first and second layers. 
     In some embodiments, each of the first layer and the second layer can be substantially free of a piezoelectric material. 
     In some embodiments, each of the first layer and the second layer can be substantially free of a piezoelectric property. 
     In some implementations, the present disclosure relates to a method for manufacturing an electrical device. The method includes providing or forming a first layer and a second layer, with each having an outer surface and an inner surface, and the first layer including a metal oxide material. The method further includes forming an inner electrode on the inner surface of each of the first and second layers, and joining the first layer and the second layer with an interface, such that the inner surfaces of the first and second layers define a sealed chamber therebetween. The method further includes forming an outer electrode on the outer surface of each of the first and second layers, such that the first outer electrode, the first layer, and the first inner electrode provide a metal oxide varistor (MOV) functionality, and the first inner electrode, the second inner electrode, and the sealed chamber provide a gas discharge tube (GDT) functionality. 
     In some embodiments, at least some of the steps can be performed in a discrete format. 
     In some embodiments, at least some of the steps can be performed in an array format in which a plurality of units are joined in an array, with each unit corresponding to a partially or completely fabricated form of the electrical device. The method can further include singulating the array to produce a plurality of individual units. 
     In some embodiments, the forming of the outer electrodes on the respective outer surfaces of the first and second layers can be performed substantially at the same time. 
     For purposes of summarizing the disclosure, certain aspects, advantages and novel features of the inventions have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment of the invention. Thus, the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a side sectional view of a device having a combination of a first metal oxide varistor (MOV) device, a gas discharge tube (GDT) device, and a second MOV device, implemented in series. 
         FIG. 2  shows a GDT/MOV device that can provide electrical functionalities similar to the example of  FIG. 1 , but in which structures and/or fabrication methods can be significantly simplified. 
         FIG. 3  shows that in some embodiments, a GDT/MOV device can include a sealed chamber having opposing sides, similar to the example of  FIG. 2 . 
         FIG. 4  shows a more specific example of the GDT/MOV device of  FIG. 2 . 
         FIGS. 5A-5G  show an example process that can be implemented to fabricate the GDT/MOV device of  FIG. 4 . 
         FIG. 6  shows another more specific example of the GDT/MOV device of  FIG. 2 . 
         FIGS. 7A-7I  show an example process that can be implemented to fabricate the GDT/MOV device of  FIG. 6 . 
         FIG. 8  shows yet another more specific example of the GDT/MOV device of  FIG. 2 . 
         FIGS. 9A-9I  show an example process that can be implemented to fabricate the GDT/MOV device of  FIG. 8 . 
         FIG. 10  shows yet another more specific example of the GDT/MOV device of  FIG. 2 . 
         FIGS. 11A-11E  show an example process that can be implemented to fabricate the GDT/MOV device of  FIG. 10 . 
         FIGS. 12A-12H  show various stages of a fabrication process in which GDT/MOV devices similar to the GDT/MOV device of  FIG. 4  can be fabricated in an array format. 
         FIGS. 13A-13J  show various stages of a fabrication process in which GDT/MOV devices similar to the GDT/MOV device of  FIG. 6  can be fabricated in an array format. 
         FIGS. 14A-14F  show various stages of a fabrication process in which GDT/MOV devices similar to the GDT/MOV device of  FIG. 8  can be fabricated in an array format. 
         FIG. 15  shows that in some embodiments, a GDT/MOV can include a first metal oxide layer and a second metal oxide layer, and a plurality of GDT chambers implemented between the first and second metal oxide layers. 
         FIG. 16  shows that in some embodiments, a GDT/MOV device can include two GDT chambers that are in gas-communication with each other. 
         FIG. 17  shows that in some embodiments, a GDT/MOV device can include a GDT chamber facilitated by a plurality of inner electrodes on one side, and a plurality of inner electrodes on the other side. 
         FIG. 18  shows that in some embodiments, an outer electrode functionality can be provided by a plurality of electrodes. 
         FIG. 19  shows that in some embodiments, a GDT/MOV device can include a GDT chamber and three MOV elements associated with the GDT chamber. 
         FIG. 20  shows that in some embodiments, two GDT/MOV devices can be implemented in series, in an integrated manner. 
         FIG. 21  shows that in some embodiments, a GDT/MOV device having one or more features as described herein can be arranged in series with a thermal fuse. 
         FIG. 22  shows that in some embodiments, a GDT/MOV device having one or more features as described herein can be arranged in series with a thermal switch. 
     
    
    
     DETAILED DESCRIPTION OF SOME EMBODIMENTS 
     The headings provided herein, if any, are for convenience only and do not necessarily affect the scope or meaning of the claimed invention. 
     Disclosed herein are various examples of devices and methods related to integration of one or more gas discharge tubes (GDTs) with one or more metal oxide varistors (MOVs). For purposes of description, a device having such integration of GDT(s) and MOV(s) can be referred to herein as a GDT/MOV device, or simply as a GDT/MOV. 
     It is noted that a typical MOV by itself can degrade due to, for example, a constant AC line voltage stress. Such a stress can result from surge history, time, temperature, or some combination thereof, and result in an increase in leakage current, and/or a decrease in effectiveness of the MOV (e.g., maximum continuous operating voltage (MCOV)). The increase in leakage current can negatively impact an energy efficiency rating of the MOV due to an increase in a stand-by current. Also, sustained AC voltage swells can result in overheating of the MOV which in turn can result in failure and/or fire. 
     When an MOV is combined with a GDT, the resulting combination can be a GDT/MOV device having a GDT and an MOV electrically connected in series. When operating under normal conditions, a line (e.g., an AC line) voltage appears largely across the GDT, thereby effectively disconnecting the MOV from the line. During a surge event, the GDT can switch on relatively quickly, and thereby connect the MOV across the line to clamp the surge voltage to an acceptable level. Once the surge event has passed, the GDT can switch off again and thereby disconnect the MOV as before. 
     Accordingly, a GDT/MOV device can provide a number of advantageous features. For example, reduced leakage current in the MOV portion can be achieved, which can extend the operating life of the device. In another example, a GDT/MOV device can be designed to provide voltage swell immunity, or reduced sensitivity to such a voltage swell, without sacrificing clamping voltage performance. 
       FIG. 1  shows a side sectional view of a device  50  having a combination of a first MOV device  54 , a GDT device  56 , and a second MOV device  58 , implemented in series.  FIG. 1  also shows an electrical circuit representation  52  of the device  50 . In the example of  FIG. 1 , the first MOV device  54  includes its own terminals  60 ,  64  implemented on opposing sides of a metal oxide layer  62 . Similarly, the second MOV device  58  includes its own terminals  86 ,  90  implemented on opposing sides of a metal oxide layer  88 . 
     Between the first and second MOV devices  54 ,  58  is the GDT device  56  with its own terminals  66 ,  84  on opposing sides of the GDT device  56 . The GDT device  56  itself is shown to include a middle layer  72  with an opening, and first and second layers  68 ,  82  on opposing sides of the middle layer  72 , so as to form a sealed chamber  76  defined by the opening of the middle layer  72  and inner facing surfaces of the first and second layers  68 ,  82 . 
     Within the foregoing sealed chamber  76  are first and second electrodes  74 ,  78  of the GDT device  56 . The first electrode  74  is shown to be electrically connected to the first terminal  66  (electrical connection depicted as dashed line  70 ), and the second electrode  78  is shown to be electrically connected to the second terminal  84  (electrical connection depicted as dashed line  80 ). 
     Examples related to the foregoing GDT device  56  can be found in U.S. Pat. No. 10,032,621 titled FLAT GAS DISCHARGE TUBE DEVICES AND METHODS, which is hereby expressly incorporated by reference herein in its entirety, and its disclosure is to be considered part of the specification of the present application. It will be understood that other designs of GDT devices can be utilized in the example of  FIG. 1 . 
     In the example of  FIG. 1 , the second terminal  64  of the first MOV device  54  is in physical contact with the first terminal  66  of the GDT device  56 . Similarly, the first terminal  86  of the second MOV device  58  is in physical contact with the second terminal  84  of the GDT device  56 . Accordingly, the first terminal  60  of the first MOV device  54  and the second terminal  90  of the second MOV device  58  can be utilized as overall terminals of the device  50 . 
     In the example of  FIG. 1 , the three layers ( 72 ,  68 ,  82 ) of the GDT device  56  can be implemented as electrically insulating layers formed from electrically insulating materials, including the examples disclosed in the above-referenced U.S. Pat. No. 10,032,621. It is noted that with use of such insulating materials for the first and second layers  68 ,  82  in the GDT device  56 , the electrical connections  70 ,  80  are needed to connect the electrodes  74 ,  78  to their respective terminals ( 66 ,  84 ). Examples of such electrical connections (internal and/or external connections) can also be found in U.S. Pat. No. 10,032,621. 
       FIG. 2  shows a GDT/MOV device that can provide electrical functionalities similar to the example of  FIG. 1 , but in which structures and/or fabrication methods can be significantly simplified.  FIG. 2  shows that in some embodiments, a GDT/MOV device  100  can include a sealed chamber  116  having opposing sides. A first electrode  114  is shown to be implemented on one of such opposing sides, and a second electrode  118  is shown to be implemented on the other side, thereby providing a GDT configuration  106  (also referred to as a GDT herein). 
     The first electrode  114  of the GDT  106  is also shown to function as one of two electrodes of a first MOV configuration  104  (also referred to as an MOV herein). More particularly, a metal oxide layer  112  is shown to be implemented between the first electrode  114  of the GDT  106  and a first external electrode  110 , thereby providing the first MOV functionality. 
     Similarly, the second electrode  118  of the GDT  106  is also shown to function as one of two electrodes of a second MOV configuration  108  (also referred to as an MOV herein). More particularly, a metal oxide layer  120  is shown to be implemented between the second electrode  118  of the GDT  106  and a second external electrode  122 , thereby providing the second MOV functionality. 
     In  FIG. 2 , a circuit representation  102  of the GDT/MOV device  100  is depicted as including a series arrangement of the first MOV  104 , the GDT  106 , and the second MOV  108 . In such a circuit representation, the first MOV  104  is depicted as having one of its electrodes also function as one of the electrodes of the GDT  106 . Thus, in the structure shown in  FIG. 2 , the electrode  114  can be referred to as a first shared electrode. Similarly, the second MOV  108  is depicted as having one of its electrodes also function as the other of the electrodes of the GDT  106 . Thus, in the structure shown in  FIG. 2 , the electrode  118  can be referred to as a second shared electrode. 
     In the example of  FIG. 2 , at least some of the layer  112  between the first external electrode  110  and the first shared electrode  114  can include metal oxide material suitable to provide MOV functionality between the electrodes  110 ,  114 . Similarly, at least some of the layer  120  between the second external electrode  122  and the second shared electrode  118  can include metal oxide material suitable to provide MOV functionality between the electrodes  122 ,  118 . 
     In some embodiments, an edge region (indicated as  115  in  FIG. 2 ) can include an insulating portion to provide electrical insulation between the first metal oxide layer  112  and the second metal oxide layer  120 . In some embodiments, the metal oxide material of the first layer  112  may or may not extend into the edge region  115 . Similarly, the metal oxide material of the second layer  120  may or may not extend into the edge region  115 . Various non-limiting examples of the edge region  115  are described herein in greater details. 
     In the example of  FIG. 2 , the GDT/MOV device  100  provides a functionality of two MOVs ( 104 ,  108 ) with a GDT ( 106 ) in between, arranged in series. It will be understood that one or more features of the present disclosure can also be implemented with a GDT/MOV device having less than two MOVs. 
     For example,  FIG. 3  shows that in some embodiments, a GDT/MOV device  100  can include a sealed chamber  116  having opposing sides, similar to the example of  FIG. 2 . A first electrode  114  is shown to be implemented on one of such opposing sides, and a second electrode  118  is shown to be implemented on the other side, thereby providing a GDT configuration  106 . 
     The first electrode  114  of the GDT  106  is also shown to function as one of two electrodes of an MOV configuration  104 . More particularly, a metal oxide layer  112  is shown to be implemented between the first electrode  114  of the GDT  106  and a first external electrode  110 , thereby providing the MOV functionality. 
     Unlike the example of  FIG. 2 , an electrically insulating layer  124  is shown to be provided between the second electrode  118  of the GDT  106  and a second external electrode  122 . Further, the second electrode  118  of the GDT  106  is shown to be electrically connected (depicted as  125 ) to the second external electrode  122 , such that the assembly generally indicated as  106  provides the GDT functionality. 
     In  FIG. 3 , a circuit representation  102  of the GDT/MOV device  100  is depicted as including a series arrangement of the MOV  104  and the GDT  106 . In such a circuit representation, the MOV  104  is depicted as having one of its electrodes also function as one of the electrodes of the GDT  106 . Thus, in the structure shown in  FIG. 3 , the electrode  114  can be referred to as a shared electrode. Since there is no second MOV in this example, the other electrode ( 118 ) of the GDT  106  is not a shared electrode. 
     In the example of  FIG. 3 , at least some of the layer  112  between the first external electrode  110  and the shared electrode  114  can include metal oxide material suitable to provide MOV functionality between the electrodes  110 ,  114 . Also in the example of  FIG. 3 , at least some of the layer  124  between the second external electrode  122  and the second electrode  118  of the GDT  106  can include an electrically insulating material suitable to provide GDT functionality. 
     In some embodiments, an edge region (indicated as  117  in  FIG. 3 ) can include an insulating material, a metal oxide material, or some combination thereof. 
       FIG. 4  shows a more specific example of the GDT/MOV device  100  of  FIG. 2 . More particularly,  FIG. 4  shows that in some embodiments, a GDT/MOV device  100  can include a first MOV ( 104  in  FIG. 2 ) with a metal oxide layer  112  and a second MOV ( 108  in  FIG. 2 ) with a metal oxide layer  120 , with each MOV having a pocket defined by a raised perimeter. Thus, when such MOVs are assembled with the pockets facing each other, a GDT chamber  116  is formed. 
     As shown in  FIG. 4 , a seal  130  can be implemented so as to join the raised perimeter portions of the first and second MOVs. In some embodiments, such a seal can be an electrically insulating seal, such as a glass seal. Examples related to formation of glass seals can be found in U.S. patent application Ser. No. 15/990,965 and the corresponding U.S. Publication No. 2019/0074162 titled GLASS SEALED GAS DISCHARGE TUBES, each of which is hereby expressly incorporated by reference herein in its entirety, and its disclosure is to be considered part of the specification of the present application. 
     In the example of  FIG. 4 , the first MOV is shown to include an inner electrode  114  on the inner-facing pocket surface of the metal oxide layer  112 . The same inner electrode  114  for the first MOV is shown to be utilized as a first electrode of the GDT chamber  116 . Similarly, second MOV is shown to include an inner electrode  118  on the inner-facing pocket surface of the metal oxide layer  120 . The same inner electrode  118  for the second MOV is shown to be utilized as a second electrode of the GDT chamber  116 . 
       FIG. 4  shows that in some embodiments, an emissive coating ( 132  or  134 ) can be provided on each of the electrodes  114 ,  118 . Such an emissive coating can be utilized for operation of the GDT portion of the GDT/MOV device  100 . It will be understood that a GDT/MOV device having one or more features as described herein may or may not include emissive coatings on electrodes. 
     In the example of  FIG. 4 , first and second outer electrodes  110 ,  122  are shown to be implemented on the outer sides of the first and second metal oxide layers  112 ,  120 , respectively. Thus, the first MOV can include the first metal oxide layer  112  implemented between the first outer electrode  110  and the first inner electrode  114 . Similarly, the second MOV can include the second metal oxide layer  120  implemented between the second outer electrode  122  and the second inner electrode  118 . 
       FIGS. 5A-5G  show various stages of an example process that can be implemented to fabricate the GDT/MOV device  100  of  FIG. 4 .  FIG. 5A  shows that in some embodiments, a metal oxide layer can be provided or formed. In some embodiments, such a metal oxide layer can be utilized as the first metal oxide layer  112  or the second metal oxide layer  120  of  FIG. 4 . Accordingly, the metal oxide layer in  FIG. 5A  is indicated as  112 ,  120 . However, it will be understood that in some embodiments, a metal oxide layer for the first MOV may be different than a metal oxide layer for the second MOV. 
     In the example of  FIG. 5A , the metal oxide layer  112 ,  120  is shown to include a pocket  140  defined by a raised perimeter portion  142 . In some embodiments, the metal oxide layer  112 ,  120  can be formed by a molding process or any other process suitable for fabrication of MOVs. 
       FIG. 5B  shows that in some embodiments, an inner electrode (indicated as  114 ,  118 ) can be formed on an inner-facing surface (e.g., on the floor) of the pocket ( 140  in  FIG. 5A ), so as to form an assembly  144 . Thus, in the context of the metal oxide layer  112 ,  120  being utilized for the first metal oxide layer  112  and the second metal oxide layer  120  of  FIG. 4 , the same inner electrode ( 114 ,  118 ) can be utilized for the first metal oxide layer  112  and the second metal oxide layer  120 . It will be understood that in some embodiments, the first and second inner electrodes may or may not be the same. 
       FIG. 5C  shows that in some embodiments, an emissive coating (indicated as  132 ,  134 ) can be formed on an inner-facing surface of the respective inner electrode ( 114 ,  118 ), so as to form an assembly  146 . It will be understood that in some embodiments, emissive coatings for the first and second inner electrodes may or may not be the same. 
       FIG. 5D  shows that in some embodiments, a layer  148  of sealing material can be formed on the raised perimeter portion ( 142  in  FIG. 5A ), so as to form an assembly  150 . In some embodiments, such a sealing material can be an electrically insulating material such as an insulative sealing glass or other high temperature insulative sealing material. 
       FIG. 5E  shows that in some embodiments, two of the assemblies  150  of  FIG. 5D  can be assembled to allow joining of the inner facing portions of the two assemblies. More particularly, a first assembly  150   a  (similar to the assembly  150  of  FIG. 5D ) can be inverted and positioned over a second assembly  150   b  (also similar to the assembly  150  of  FIG. 5D ), so as to form an assembly  152 . 
       FIG. 5F  shows that in some embodiments, the assembly  152  of  FIG. 5E  can be further processed to form a seal  130  and a corresponding sealed chamber  116 , so as to form an assembly  154 . By way of an example, such further processing of the assembly  152  of  FIG. 5E  can include providing a desired gas (e.g., inert gas, active gas, or some combination thereof) so that the unsealed chamber becomes filled with the gas. Then, the assembly  152  can be heated so that the sealing layers ( 148  in  FIG. 5D ) fuse to form the seal  130  and the sealed chamber  116  with the desired gas therein. 
       FIG. 5G  shows that in some embodiments, first and second external electrodes  110 ,  122  can be formed on the assembly  154  of  FIG. 5F , so as to form an assembly  100  that is similar to the GDT/MOV device  100  of  FIG. 4 . More particularly, the first external electrode  110  can be formed on the outer facing surface of the first metal oxide layer ( 112  in  FIG. 4 ), and the second external electrode  122  can be formed on the outer facing surface of the second metal oxide layer ( 120  in  FIG. 4 ). 
     In the examples of  FIGS. 4 and 5A-5G , the interface portion ( 115  in  FIG. 2 ) between the two MOVs can include the raised perimeter portions ( 142  in  FIG. 5A ). In some embodiments, such raised perimeter portions can be formed from the same metal oxide material that forms the remaining portions of the metal oxide layers ( 112 ,  120  in  FIG. 4 ). 
     It is noted that in the examples of  FIGS. 4 and 5A-5G , an electrically insulating property of the interface portion ( 115  in  FIG. 2 ) between the two MOVs can be provided by the electrically insulating seal  130 , as shown in  FIGS. 4, 5F and 5G . 
       FIG. 6  shows another more specific example of the GDT/MOV device  100  of  FIG. 2 . More particularly,  FIG. 6  shows that in some embodiments, a GDT/MOV device  100  can include a first MOV ( 104  in  FIG. 2 ) with a metal oxide layer  112  and a second MOV ( 108  in  FIG. 2 ) with a metal oxide layer  120 . In the example of  FIG. 6 , each of the two metal oxide layers  112 ,  120  can be a substantially flat layer. Thus, when such MOVs are assembled with a spacer  160  therebetween, a GDT chamber  116  is formed. 
     In some embodiments, the spacer  160  can be implemented as a plate having an opening therethrough, and such an opening can generally define the side wall of the GDT chamber  116  when sealed. 
     As shown in  FIG. 6 , a first seal  162  can be implemented so as to join the perimeter portion of the metal oxide layer  112  of the first MOV and the spacer  160 , and a second seal  164  can be implemented so as to join the perimeter portion of the metal oxide layer  120  of the second MOV and the spacer  160 . 
     In the example of  FIG. 6 , at least one of the first seal  162 , the spacer  160 , and the second seal  164  can be an electrically insulating part. For example, if the spacer  160  is formed from an electrically insulating material (e.g., ceramic), each of the first and second seals  162 ,  164  can be formed from an electrically conducting material (e.g., metal) or an electrically insulating material (e.g., glass). In another example, if either or both of the first and second seals  162 ,  164  is/are formed from an electrically insulating material (e.g., glass), the spacer  162  can be formed from an electrically conducting material (e.g., metal) or an electrically insulating material (e.g., ceramic). 
     For the purpose of description of  FIGS. 6 and 7A-7I , it will be assumed that the spacer  162  is formed from an electrically insulating material such as ceramic, and the first and second seals  162 ,  164  are formed from an electrically insulating material such as glass or an electrically conducting material such as metal. However, it will be understood that other configurations are also possible, as described above. 
     In the example of  FIG. 6 , the first MOV is shown to include an inner electrode  114  on the inner-facing surface of the metal oxide layer  112 . The same inner electrode  114  for the first MOV is shown to be utilized as a first electrode of the GDT chamber  116 . Similarly, second MOV is shown to include an inner electrode  118  on the inner-facing surface of the metal oxide layer  120 . The same inner electrode  118  for the second MOV is shown to be utilized as a second electrode of the GDT chamber  116 . 
       FIG. 6  shows that in some embodiments, an emissive coating ( 132  or  134 ) can be provided on each of the electrodes  114 ,  118 . Such an emissive coating can be utilized for operation of the GDT portion of the GDT/MOV device  100 . It will be understood that a GDT/MOV device having one or more features as described herein may or may not include emissive coatings on electrodes. 
     In the example of  FIG. 6 , first and second outer electrodes  110 ,  122  are shown to be implemented on the outer sides of the first and second metal oxide layers  112 ,  120 , respectively. Thus, the first MOV can include the first metal oxide layer  112  implemented between the first outer electrode  110  and the first inner electrode  114 . Similarly, the second MOV can include the second metal oxide layer  120  implemented between the second outer electrode  122  and the second inner electrode  118 . 
       FIGS. 7A-7I  show various stages of an example process that can be implemented to fabricate the GDT/MOV device  100  of  FIG. 6 .  FIG. 7A  shows that in some embodiments, a spacer layer  160  can be provided or formed. Such a spacer layer can include and opening  170  dimensioned to become the chamber of the GDT portion of the GDT/MOV device. In some embodiments, the opening  170  can be formed on a solid layer by, for example, punching or cutting out a desired shape of the opening  170 . In some embodiments, the spacer layer  160  can be pre-formed with the opening. In some embodiments, the spacer layer  160  can be formed from, for example, ceramic material. 
       FIG. 7B  shows that in some embodiments, a sealing layer  172  can be provided on one side of the perimeter portion of the spacer layer  160 , and another sealing layer  174  can be provided on the other side of the perimeter portion of the spacer layer  160 , so as to form an assembly  176 . In some embodiments, each of the sealing layers  172 ,  174  can be formed from, for example, an electrically insulating material such as an insulative sealing glass or other high temperature insulative sealing material. 
       FIG. 7C  shows that in some embodiments, a metal oxide layer can be provided or formed. In some embodiments, such a metal oxide layer can be utilized as the first metal oxide layer  112  or the second metal oxide layer  120  of  FIG. 6 . Accordingly, the metal oxide layer in  FIG. 7C  is indicated as  112 ,  120 . However, it will be understood that in some embodiments, a metal oxide layer for the first MOV may be different than a metal oxide layer for the second MOV. 
       FIG. 7C  shows that in some embodiments, the metal oxide layer  112 ,  120  can be substantially flat. In some embodiments, the metal oxide layer  112 ,  120  can be formed by a molding process or any other process suitable for fabrication of MOVs. 
       FIG. 7D  shows that in some embodiments, an inner electrode (indicated as  114 ,  118 ) can be formed on an inner-facing surface of the metal oxide layer  112 ,  120 , so as to form an assembly  178 . Thus, in the context of the metal oxide layer  112 ,  120  being utilized for the first metal oxide layer  112  and the second metal oxide layer  120  of  FIG. 6 , the same inner electrode ( 114 ,  118 ) can be utilized for the first metal oxide layer  112  and the second metal oxide layer  120 . It will be understood that in some embodiments, the first and second inner electrodes may or may not be the same. 
       FIG. 7E  shows that in some embodiments, an emissive coating (indicated as  132 ,  134 ) can be formed on an inner-facing surface of the respective inner electrode ( 114 ,  118 ), so as to form an assembly  180 . It will be understood that in some embodiments, emissive coatings for the first and second inner electrodes may or may not be the same. 
       FIG. 7F  shows that in some embodiments, a layer  182  of sealing material can be formed on the perimeter portion of the inner-facing surface of the metal oxide layer  112 ,  120 , so as to form an assembly  184 . In some embodiments, such a sealing material can be an electrically insulating material such as an insulative sealing glass or other high temperature insulative sealing material. 
       FIG. 7G  shows that in some embodiments, two of the assemblies  184  of  FIG. 7F  and the assembly  176  of  FIG. 7B  can be assembled to allow joining of the inner facing portions of the two assemblies  184  by the assembly  176 . More particularly, a first assembly  184   a  (similar to the assembly  184  of  FIG. 7F ) can be inverted and positioned over the spacer/sealing layer assembly  176 , and a second assembly  184   b  (also similar to the assembly  184  of  FIG. 7F ) can be positioned under the spacer/sealing layer assembly  176 , so as to form an assembly  186 . 
       FIG. 7H  shows that in some embodiments, the assembly  186  of  FIG. 7G  can be further processed to form seals  162 ,  164  on both sides of the spacer layer  160  and a corresponding sealed chamber  116 , so as to form an assembly  188 . By way of an example, such further processing of the assembly  186  of  FIG. 7G  can include providing a desired gas (e.g., inert gas, active gas, or some combination thereof) so that the unsealed chamber becomes filled with the gas. Then, the assembly  186  can be heated so that the respective sealing layers ( 172  and  182 , and  174  and  182 , in  FIGS. 7B and 7F ) fuse to form the seals  162 ,  164  on both sides of the spacer  160  and the sealed chamber  116  with the desired gas therein. 
       FIG. 7I  shows that in some embodiments, first and second external electrodes  110 ,  122  can be formed on the assembly  188  of  FIG. 7H , so as to form an assembly  100  that is similar to the GDT/MOV device  100  of  FIG. 6 . More particularly, the first external electrode  110  can be formed on the outer facing surface of the first metal oxide layer ( 112  in  FIG. 6 ), and the second external electrode  122  can be formed on the outer facing surface of the second metal oxide layer ( 120  in  FIG. 6 ). 
       FIG. 8  shows yet another more specific example of the GDT/MOV device  100  of  FIG. 2 . More particularly,  FIG. 8  shows that in some embodiments, a GDT/MOV device  100  can include a first MOV ( 104  in  FIG. 2 ) with a metal oxide layer  112  and a second MOV ( 108  in  FIG. 2 ) with a metal oxide layer  120 . In the example of  FIG. 8 , each of the two metal oxide layers  112 ,  120  can be a substantially flat layer, similar to the example of  FIG. 6 . Thus, when such MOVs are assembled with a spacer  190  therebetween, a GDT chamber  116  is formed. 
     In some embodiments, the spacer  190  can be implemented as a plate having an opening therethrough, similar to the example spacer  160  of  FIG. 6 . In the example of  FIG. 8 , however, the spacer  190  is shown to be dimensioned so that its lateral outer portion extends beyond an outer side wall defined by the first and second metal oxide layers  112 ,  120 . As described herein, the foregoing extension of the spacer can be referred to as a “wing.” Examples related to such wings can be found in U.S. Pat. No. 9,202,682 titled DEVICES AND METHODS RELATED TO FLAT GAS DISCHARGE TUBES, which is hereby expressly incorporated by reference herein in its entirety, and its disclosure is to be considered part of the specification of the present application. 
     As also described herein, and in some embodiments, such a wing configuration can allow multiple GDT/MOV devices to be fabricated in an array format and be singulated in a manner that is different than a singulation technique that may be utilized after an array-format fabrication of multiple GDT/MOV devices similar to the example of  FIG. 6 . Examples of such array-format fabrications are described herein in greater detail. In some embodiments, the lateral inner portion of the spacer  190  may or may not extend inward beyond the inner edge of seals  192 ,  194  on both sides of the spacer  190 . 
     As shown in  FIG. 8 , a first seal  192  can be implemented so as to join the perimeter portion of the metal oxide layer  112  of the first MOV and the spacer  190 , and a second seal  194  can be implemented so as to join the perimeter portion of the metal oxide layer  120  of the second MOV and the spacer  190 . 
     In the example of  FIG. 8 , at least one of the first seal  192 , the spacer  190 , and the second seal  194  can be an electrically insulating part. For example, if the spacer  190  is formed from an electrically insulating material (e.g., ceramic), each of the first and second seals  192 ,  194  can be formed from an electrically conducting material (e.g., metal) or an electrically insulating material (e.g., glass). In another example, if either or both of the first and second seals  192 ,  194  is/are formed from an electrically insulating material (e.g., glass), the spacer  192  can be formed from an electrically conducting material (e.g., metal) or an electrically insulating material (e.g., ceramic). 
     For the purpose of description of  FIGS. 8 and 9A-9I , it will be assumed that the spacer  192  is formed from an electrically insulating material such as ceramic, and the first and second seals  192 ,  194  are formed from an electrically insulating material such as glass or an electrically conducting material such as metal. However, it will be understood that other configurations are also possible, as described above. 
     In the example of  FIG. 8 , the first MOV is shown to include an inner electrode  114  on the inner-facing surface of the metal oxide layer  112 . The same inner electrode  114  for the first MOV is shown to be utilized as a first electrode of the GDT chamber  116 . Similarly, second MOV is shown to include an inner electrode  118  on the inner-facing surface of the metal oxide layer  120 . The same inner electrode  118  for the second MOV is shown to be utilized as a second electrode of the GDT chamber  116 . 
       FIG. 8  shows that in some embodiments, an emissive coating can be provided on each of the electrodes  114 ,  118 . Such an emissive coating can be utilized for operation of the GDT portion of the GDT/MOV device  100 . It will be understood that a GDT/MOV device having one or more features as described herein may or may not include emissive coatings on electrodes. 
     In the example of  FIG. 8 , first and second outer electrodes  110 ,  122  are shown to be implemented on the outer sides of the first and second metal oxide layers  112 ,  120 , respectively. Thus, the first MOV can include the first metal oxide layer  112  implemented between the first outer electrode  110  and the first inner electrode  114 . Similarly, the second MOV can include the second metal oxide layer  120  implemented between the second outer electrode  122  and the second inner electrode  118 . 
       FIGS. 9A-9I  show various stages of an example process that can be implemented to fabricate the GDT/MOV device  100  of  FIG. 8 .  FIG. 9A  shows that in some embodiments, a spacer layer  190  can be provided or formed. Such a spacer layer can include and opening  200  dimensioned to generally become the chamber of the GDT portion of the GDT/MOV device. In some embodiments, the opening  200  can be formed on a solid layer by, for example, punching or cutting out a desired shape of the opening  200 . In some embodiments, the spacer layer  190  can be pre-formed with the opening. In some embodiments, the spacer layer  190  can be formed from, for example, ceramic material. 
       FIG. 9B  shows that in some embodiments, a sealing layer  202  can be provided on one side of the near-perimeter portion of the spacer layer  190 , and another sealing layer  204  can be provided on the other side of the near-perimeter portion of the spacer layer  190 , so as to form an assembly  206 . In some embodiments, the sealing layers  202 ,  204  can be positioned inward from the outer edge of the spacer layer  190  so as to allow formation of the wing, where the outer portion of the spacer layer  190  extends outward beyond the side wall defined by the first and second metal oxide layers  112 ,  120 . In some embodiments, each of the sealing layers  202 ,  204  can be formed from, for example, an electrically insulating material such as an insulative sealing glass or other high temperature insulative sealing material. 
       FIG. 9C  shows that in some embodiments, a metal oxide layer can be provided or formed. In some embodiments, such a metal oxide layer can be utilized as the first metal oxide layer  112  or the second metal oxide layer  120  of  FIG. 8 . Accordingly, the metal oxide layer in  FIG. 9C  is indicated as  112 ,  120 . However, it will be understood that in some embodiments, a metal oxide layer for the first MOV may be different than a metal oxide layer for the second MOV. 
       FIG. 9C  shows that in some embodiments, the metal oxide layer  112 ,  120  can be substantially flat. In some embodiments, the metal oxide layer  112 ,  120  can be formed by a molding process or any other process suitable for fabrication of MOVs. 
       FIG. 9D  shows that in some embodiments, an inner electrode (indicated as  114 ,  118 ) can be formed on an inner-facing surface of the metal oxide layer  112 ,  120 , so as to form an assembly  208 . Thus, in the context of the metal oxide layer  112 ,  120  being utilized for the first metal oxide layer  112  and the second metal oxide layer  120  of  FIG. 8 , the same inner electrode ( 114 ,  118 ) can be utilized for the first metal oxide layer  112  and the second metal oxide layer  120 . It will be understood that in some embodiments, the first and second inner electrodes may or may not be the same. 
       FIG. 9E  shows that in some embodiments, an emissive coating (indicated as  132 ,  134 ) can be formed on an inner-facing surface of the respective inner electrode ( 114 ,  118 ), so as to form an assembly  210 . It will be understood that in some embodiments, emissive coatings for the first and second inner electrodes may or may not be the same. 
       FIG. 9F  shows that in some embodiments, a layer  212  of sealing material can be formed on the perimeter portion of the inner-facing surface of the metal oxide layer  112 ,  120 , so as to form an assembly  214 . In some embodiments, such a sealing material can be an electrically insulating material such as an insulative sealing glass or other high temperature insulative sealing material. 
       FIG. 9G  shows that in some embodiments, two of the assemblies  214  of  FIG. 9F  and the assembly  206  of  FIG. 9B  can be assembled to allow joining of the inner facing portions of the two assemblies  214  by the assembly  206 . More particularly, a first assembly  214   a  (similar to the assembly  214  of  FIG. 9F ) can be inverted and positioned over the spacer/sealing layer assembly  206 , and a second assembly  214   b  (also similar to the assembly  214  of  FIG. 9F ) can be positioned under the spacer/sealing layer assembly  206 , so as to form an assembly  216 . 
       FIG. 9H  shows that in some embodiments, the assembly  216  of  FIG. 9G  can be further processed to form seals  192 ,  194  on both sides of the spacer layer  190  and a corresponding sealed chamber  116 , so as to form an assembly  218 . By way of an example, such further processing of the assembly  216  of  FIG. 9G  can include providing a desired gas (e.g., inert gas, active gas, or some combination thereof) so that the unsealed chamber becomes filled with the gas. Then, the assembly  216  can be heated so that the respective sealing layers ( 202  and  212 , and  204  and  212 , in  FIGS. 9B and 9F ) fuse to form the seals  192 ,  194  on both sides of the spacer  190  and the sealed chamber  116  with the desired gas therein. 
       FIG. 9I  shows that in some embodiments, first and second external electrodes  110 ,  122  can be formed on the assembly  218  of  FIG. 9H , so as to form an assembly  100  that is similar to the GDT/MOV device  100  of  FIG. 8 . More particularly, the first external electrode  110  can be formed on the outer facing surface of the first metal oxide layer ( 112  in  FIG. 8 ), and the second external electrode  122  can be formed on the outer facing surface of the second metal oxide layer ( 120  in  FIG. 8 ). 
       FIG. 10  shows yet another more specific example of the GDT/MOV device  100  of  FIG. 2 . More particularly,  FIG. 10  shows that in some embodiments, a GDT/MOV device  100  can be similar to the example of  FIG. 8 , but include a plurality of spacer layers (e.g., two spacer layers  220 ,  222 ). Thus, the GDT/MOV device  100  of  FIG. 10  can include a first MOV ( 104  in  FIG. 2 ) with a metal oxide layer  112  and a second MOV ( 108  in  FIG. 2 ) with a metal oxide layer  120 . In the example of  FIG. 10 , each of the two metal oxide layers  112 ,  120  can be a substantially flat layer, similar to the example of  FIG. 6 . Thus, when such MOVs are assembled with the spacers  220 ,  222  therebetween, a GDT chamber  116  is formed. 
     In the example of  FIG. 10 , each of the spacers  220 ,  222  can be implemented as a plate having an opening therethrough, similar to the example spacer layer  190  of  FIG. 8 . With such spacers ( 220 ,  222 ), a seal  224  can be implemented so as to join the perimeter portion of the metal oxide layer  112  of the first MOV and the spacer  220 , a seal  226  can be implemented so as to join the spacer  220  and the spacer  222 , and seal  228  can be implemented so as to join the perimeter portion of the metal oxide layer  120  of the second MOV and the spacer  222 . 
     In the example of  FIG. 10 , assuming that each of the two spacers  220 ,  222  is similar to the spacer  190  of  FIG. 8 , the additional spacer can allow the GDT portion of the GDT/MOV device  100  to support higher voltages. Thus, it will be understood that more than two of such spacers can also be utilized. 
     In the example of  FIG. 10 , first and second inner electrodes  114 ,  118 , optional emissive coatings  132 ,  134 , and first and second outer electrodes  110 ,  122  can be similar to the example of  FIG. 8 . However, it will be understood that such parts may also be different to, for example, support higher voltages. 
       FIGS. 11A-11E  show various stages of an example process that can be implemented to fabricate the GDT/MOV device  100  of  FIG. 10 . Assuming that each of the spacers  220 ,  222  of  FIG. 10  is similar to the spacer  190  of  FIG. 8 , two of the assemblies  206  of  FIG. 9B  can be provided in  FIG. 11A . Similarly, in  FIG. 11B , an assembly  214  of  FIG. 9F  can be provided for each of the two metal oxide layers  112 ,  120 . 
       FIG. 11O  shows that in some embodiments, two of the assemblies  214  of  FIG. 11B  and two of the assemblies  206  of  FIG. 11B  can be assembled to allow joining of the inner facing portions of the two assemblies  214  by the two-spacer assembly. More particularly, a first assembly  214   a  (similar to the assembly  214  of  FIG. 11B ) can be inverted and positioned over a first spacer/sealing layer assembly  206   a , which is in turn positioned over a second spacer/sealing layer assembly  206   b . A second assembly  214   b  (also similar to the assembly  214  of  FIG. 11B ) can be positioned under the second spacer/sealing layer assembly  206   b , so as to form an assembly  230 . 
       FIG. 11D  shows that in some embodiments, the assembly  230  of  FIG. 11C  can be further processed to form seals  224 ,  226 ,  228  between the respective layers, so as to form an assembly  232 . By way of an example, such further processing of the assembly  230  of  FIG. 11O  can include providing a desired gas (e.g., inert gas, active gas, or some combination thereof) so that the unsealed chamber becomes filled with the gas. Then, the assembly  230  can be heated so that the respective sealing layers ( 202 ,  204 ,  212  of  FIGS. 11A and 11B ) fuse to form the seals  224 ,  226 ,  228  between the respective layers and the sealed chamber  116  with the desired gas therein. 
       FIG. 11E  shows that in some embodiments, first and second external electrodes  110 ,  122  can be formed on the assembly  232  of  FIG. 11D , so as to form an assembly  100  that is similar to the GDT/MOV device  100  of  FIG. 10 . More particularly, the first external electrode  110  can be formed on the outer facing surface of the first metal oxide layer ( 112  in  FIG. 10 ), and the second external electrode  122  can be formed on the outer facing surface of the second metal oxide layer ( 120  in  FIG. 10 ). 
     In the examples described in reference to  FIGS. 4-11 , the respective GDT/MOV devices  100  are depicted as being fabricated as single units. It will be understood that in some embodiments, some or all of such GDT/MOV devices can be fabricated in discrete units (e.g., as single units), in array formats, or any combination thereof. 
     For example,  FIGS. 12A-12H  show various stages of a fabrication process in which GDT/MOV devices (similar to the GDT/MOV device  100  of  FIG. 4 ) are fabricated in an array format. In another example,  FIGS. 13A-13J  show various stages of a fabrication process in which GDT/MOV devices (similar to the GDT/MOV device  100  of  FIG. 6 ) are fabricated in an array format. In yet another example,  FIGS. 14A-14F  show various stages of a fabrication process in which GDT/MOV devices (similar to the GDT/MOV device  100  of  FIG. 8 ) are fabricated in an array format. 
     Referring to  FIG. 12A , an array  300  having a plurality of units (each unit indicated as  112 ,  120 ) can be provided or formed. Each unit can be similar to the metal oxide layer  112 ,  120  of  FIG. 5A ; thus, the array  300  of  FIG. 12A  can be an array of first metal oxide units  112 , or an array of second metal oxide units  120 . Accordingly, the array  300  can be formed in an array format, where each unit is formed similar to the example of  FIG. 5A . 
     Referring to  FIG. 12B , the array  300  of  FIG. 12A  can be processed so as to yield a plurality of units  144 , with each unit being similar to the example assembly  144  of  FIG. 5B . Accordingly, an assembly  302  can be formed in an array format, where each unit is formed similar to the example of  FIG. 5B . 
     Referring to  FIG. 12C , the assembly  302  of  FIG. 12B  can be processed so as to yield a plurality of units  146 , with each unit being similar to the example assembly  146  of  FIG. 5C . Accordingly, an assembly  304  can be formed in an array format, where each unit is formed similar to the example of  FIG. 5C . 
     Referring to  FIG. 12D , the assembly  304  of  FIG. 12C  can be processed so as to yield a plurality of units  150 , with each unit being similar to the example assembly  150  of  FIG. 5D . Accordingly, an assembly  306  can be formed in an array format, where each unit is formed similar to the example of  FIG. 5D . 
     Referring to  FIG. 12E , two of the assemblies  306  of  FIG. 12D  can be processed so as to yield a plurality of units  152 , with each unit being similar to the example assembly  152  of  FIG. 5E . Accordingly, an assembly  308  can be formed in an array format, where each unit is arranged similar to the example of  FIG. 5E . 
     Referring to  FIG. 12F , the assembly  308  of  FIG. 12E  can be processed so as to yield a plurality of units  154 , with each unit being similar to the example assembly  154  of  FIG. 5F . Accordingly, an assembly  310  can be formed in an array format, where each unit is formed similar to the example of  FIG. 5F . 
     Referring to  FIG. 12G , the assembly  310  of  FIG. 12F  can be processed so as to yield an assembly  312  that includes a plurality of joined units, with each unit being similar to the example assembly of  FIG. 5G . Accordingly, an assembly  312  can be formed in an array format, where each unit is formed similar to the example of  FIG. 5G . 
     Referring to  FIG. 12H , the assembly  312  of  FIG. 12G  can be processed so as to yield a plurality of individual units  100 , with each unit being similar to the GDT/MOV device  100  of  FIG. 5G . In some embodiments, such individual units can be obtained by singulation of the array-format assembly  312  of  FIG. 12G . In some embodiments, such singulation process can include, for example, a cutting (e.g., saw cutting, blade cutting, laser cutting, etc.) process in which the entire stack assembly between two units is cut. 
     Referring to  FIG. 13A , an array  320  having a plurality of units (each unit indicated as  160 ) can be provided or formed. Each unit can be similar to the spacer layer  160  of  FIG. 7A ; thus, the array  320  of  FIG. 13A  can be an array of spacer layer units  160 . Accordingly, the array  320  can be formed in an array format, where each unit is formed similar to the example of  FIG. 7A . 
     Referring to  FIG. 13B , the array  320  of  FIG. 13A  can be processed so as to yield a plurality of units  176 , with each unit being similar to the example assembly  176  of  FIG. 7B . Accordingly, an assembly  322  can be formed in an array format, where each unit is formed similar to the example of  FIG. 7B . 
     Referring to  FIG. 13C , an array  324  having a plurality of units (each unit indicated as  112 ,  120 ) can be provided or formed. Each unit can be similar to the metal oxide layer  112 ,  120  of  FIG. 7C , thus, the array  324  of  FIG. 13C  can be an array of first metal oxide units  112 , or an array of second metal oxide units  120 . Accordingly, the array  324  can be formed in an array format, where each unit is formed similar to the example of  FIG. 7C . 
     Referring to  FIG. 13D , the array  324  of  FIG. 13C  can be processed so as to yield a plurality of units  178 , with each unit being similar to the example assembly  178  of  FIG. 7D . Accordingly, an assembly  326  can be formed in an array format, where each unit is formed similar to the example of  FIG. 7D . 
     Referring to  FIG. 13E , the assembly  326  of  FIG. 13D  can be processed so as to yield a plurality of units  180 , with each unit being similar to the example assembly  180  of  FIG. 7E . Accordingly, an assembly  328  can be formed in an array format, where each unit is formed similar to the example of  FIG. 7E . 
     Referring to  FIG. 13F , the assembly  328  of  FIG. 13E  can be processed so as to yield a plurality of units  184 , with each unit being similar to the example assembly  180  of  FIG. 7F . Accordingly, an assembly  330  can be formed in an array format, where each unit is formed similar to the example of  FIG. 7F . 
     Referring to  FIG. 13G , two of the assemblies  330  of  FIG. 13F  and the assembly  322  of  FIG. 13B  can be processed so as to yield a plurality of units  186 , with each unit being similar to the example assembly  186  of  FIG. 7G . Accordingly, an assembly  332  can be formed in an array format, where each unit is arranged similar to the example of  FIG. 7G . 
     Referring to  FIG. 13H , the assembly  332  of  FIG. 13G  can be processed so as to yield a plurality of units  188 , with each unit being similar to the example assembly  188  of  FIG. 7H . Accordingly, an assembly  334  can be formed in an array format, where each unit is formed similar to the example of  FIG. 7H . 
     Referring to  FIG. 13I , the assembly  334  of  FIG. 13H  can be processed so as to yield an assembly  336  that includes a plurality of joined units, with each unit being similar to the example assembly of  FIG. 7I . Accordingly, an assembly  336  can be formed in an array format, where each unit is formed similar to the example of  FIG. 7I . 
     Referring to  FIG. 13J , the assembly  336  of  FIG. 13I  can be processed so as to yield a plurality of individual units  100 , with each unit being similar to the GDT/MOV device  100  of  FIG. 7I . In some embodiments, such individual units can be obtained by singulation of the array-format assembly  336  of  FIG. 13I . In some embodiments, such singulation process can include, for example, a cutting (e.g., saw cutting, blade cutting, laser cutting, etc.) process in which the entire stack assembly between two units is cut. 
     The fabrication examples of  FIGS. 12A-12H  and  FIGS. 13A-13J  are examples where substantially all of the respective processing steps can be achieved while in an array format, and the singulation step includes, for example, cutting of the entire stack assembly between two neighboring units.  FIGS. 14A-14F  show an example of a fabrication process where an array format is not utilized for all of the different layers. Accordingly, in such a fabrication process, a singulation step can include separation of units that are joined by one or more array format layers. 
     For example, and referring to  FIG. 14A , an array  350  having a plurality of units (each unit indicated as  190 ) can be provided or formed. Each unit can be similar to the wing-spacer layer  190  of  FIG. 9A ; thus, the array  350  of  FIG. 14A  can be an array of spacer layer units  190 . Accordingly, the array  350  can be formed in an array format, where each unit is formed similar to the example of  FIG. 9A . 
     In some embodiments, the array  350  of spacer layer units  190  can be configured to facilitate an easier singulation process. For example, a score feature can be provided along a line between two neighboring units  190 . During singulation, such a score feature can allow the units  190  to be separated by, for example, application of a mechanical force (e.g., snapping each unit for separation). An example of such singulation is described herein in greater detail. 
     Referring to  FIG. 14B , the array  350  of  FIG. 14A  can be processed so as to yield a plurality of units  206 , with each unit being similar to the example assembly  206  of  FIG. 9B . Accordingly, an assembly  352  can be formed in an array format, where each unit is formed similar to the example of  FIG. 9B . 
       FIG. 14C  shows that in some embodiments, an assembly  215  (that is similar to the example assembly  214  of  FIG. 9F , but with an external electrode formed thereon) can be positioned on each unit ( 206 ) of the array format assembly  352  of  FIG. 14B , so as to yield an assembly  354 . In some embodiments, the assemblies  215  can be fabricated as discrete units, as singulated units after array format steps, or some combination thereof. 
       FIG. 14D  shows that in some embodiments, the assemblies  215  can be positioned for each unit ( 206 ) of the array format assembly ( 352  in  FIG. 14B ) on each of the two sides, so as to form an assembly  356 . Thus, each unit  217  in  FIG. 14D  is shown to include two assemblies  215 . Such a unit ( 217 ) can be similar to the example assembly  216  of  FIG. 9G , but with external electrodes formed thereon. 
     Referring to  FIG. 14E , the assembly  356  of  FIG. 14D  can be processed so as to yield a plurality of joined units, with each unit being similar to the example assembly  218  of  FIG. 9H , but with external electrodes formed thereon. Accordingly, an assembly  358  can remain in an array format, where each unit is similar to the example of  FIG. 9I . 
       FIG. 14F  shows that in some embodiments, individual units can be obtained by singulation of the assembly  358  of  FIG. 14E . For example, an individual unit  100  (that is similar to the GDT/MOV device  100  of  FIG. 9I ) is shown to be separated from the neighboring unit by being snapped off at an approximately mid-location  362  of the spacer layer. In some embodiments, and as described herein, such singulation can be facilitated by, for example, a score feature at or near the mid-location  362  of the spacer layer. It will be understood that singulation of the spacer layer can also be achieved utilizing other techniques. 
     In the various examples described herein in reference to  FIGS. 4-14 , a given GDT/MOV device is assumed to include one GDT chamber. However, it will be understood that a GDT/MOV device having one or more features as described herein can include more than one GDT chamber. 
     For example,  FIG. 15  shows that in some embodiments, a GDT/MOV  100  can include a first metal oxide layer  112  and a second metal oxide layer  120 , similar to the example of  FIG. 2 . Thus, various interfaces between such metal oxide layers can be implemented, including the examples described herein. 
     In the example of  FIG. 15 , a plurality of GDT chambers are shown to be implemented between the first and second metal oxide layers  112 ,  120 . More particularly, a first GDT chamber  116   a  and a second GDT chamber  116   b  are shown to be implemented between the first and second metal oxide layers  112 ,  120 . The first GDT chamber  116   a  is shown to be associated with inner electrodes  114   a ,  118   a , and the second GDT chamber  116   b  is shown to be associated with inner electrodes  114   b ,  118   b . Accordingly, a first MOV functionality can be provided by the first metal oxide layer  112 , the inner electrodes  114   a ,  114   b , and an outer electrode  110 . Similarly, a second MOV functionality can be provided by the second metal oxide layer  120 , the inner electrodes  118   a ,  118   b , and an outer electrode  122 . 
     In the example of  FIG. 15 , the two GDT chambers ( 116   a ,  116   b ) are shown to be isolated from each other. In some embodiments, however, it may be desirable to have such GDT chambers be in communication with each other (e.g., in terms of gas). Thus,  FIG. 16  shows that in some embodiments, a GDT/MOV device  100  can include two GDT chambers  116   a ,  116   b  that are in gas-communication with each other. In  FIG. 16 , such gas communication can be achieved by, for example, an opening  380  between the two GDT chambers  116   a ,  116   b.    
     In some embodiments, the foregoing configuration of the example of  FIG. 16  may be desirable, where gas equilibrium between the two GDT chambers is needed or desired, but electrical properties associated with two generally parallel chambers are also needed or desired. In the example of  FIG. 16 , various other parts of the GDT/MOV device  100  can be similar to the example of  FIG. 15 . 
     In many of the examples disclosed herein, a given GDT chamber is assumed to have associated with it one set of inner electrodes. However, it will be understood that other numbers of inner electrodes can also be utilized. 
     For example,  FIG. 17  shows that in some embodiments, a GDT/MOV device  100  can include a GDT chamber  116  facilitated by a plurality of inner electrodes  114   a ,  114   b  on one side, and a plurality of inner electrodes  118   a ,  118   b  on the other side. The inner electrodes  114   a ,  114   b  can function as a shared electrode for a first MOV associated with a first metal oxide layer  112 . Similarly, the inner electrodes  118   a ,  118   b  can function as a shared electrode for a second MOV associated with a second metal oxide layer  120 . It will be understood that other configurations of the inner electrodes can also be implemented. For example, the inner electrode(s) associated with the first MOV may or may not be the same as the inner electrode(s) associated with the second MOV. 
     It will also be understood that the outer electrode  110  may or may not be the same as the outer electrode  122 . Further, and as shown in  FIG. 18 , an outer electrode functionality can be provided by a plurality of electrodes. For example, electrodes  110   a ,  110   b  can provide an outer electrode functionality for a first MOV associated with a first metal oxide layer  112 , and electrodes  122   a ,  122   b  can provide an outer electrode functionality for a second MOV associated with a second metal oxide layer  120 . 
       FIG. 19  shows that in some embodiments, a GDT/MOV device  100  can include a GDT chamber  116  and three MOV elements associated with the GDT chamber  116 . In the example of  FIG. 19 , the spacer layer  160 , seals  162 ,  164 , emissive coating  134 , inner electrode  118 , metal oxide layer  120 , and outer electrode  122  can be similar to the example described herein in reference to  FIG. 6 . 
     Unlike the example of  FIG. 6  where a single-piece metal oxide layer  112  is provided between a single inner electrode  114  and a single outer electrode  110 , the GDT/MOV device  100  of  FIG. 19  has two electrically isolated metal oxide layers  112   a ,  112   b  implemented on the other side of the GDT chamber  116 . In some embodiments, such two isolated metal oxide layers can be separated by an electrically insulating seal  113  (e.g., a glass seal). Such an electrically insulating seal can also provide sealing functionality for the GDT chamber  116 . 
     In the example of  FIG. 19 , an inner electrode  114   a  and an optional emissive coating  132   a  are shown to be implemented on the inner side of the metal oxide layer  112   a , and an outer electrode  110   a  is shown to be implemented on the outer side of the metal oxide layer  112   a . Similarly, an inner electrode  114   b  and an optional emissive coating  132   b  are shown to be implemented on the inner side of the metal oxide layer  112   b , and an outer electrode  110   b  is shown to be implemented on the outer side of the metal oxide layer  112   b . Accordingly, the GDT/MOV device  100  is shown to include three MOV elements associated with the two metal oxide layers  112   a ,  112   b  on one side of the GDT chamber  116  and one metal oxide layer  120  on the other side of the GDT chamber  116 . 
     In the example of  FIG. 19 , the edge region of the GDT/MOV device  100  is assumed to be similar to the example of  FIG. 6 . However, it will be understood that the device  100  of  FIG. 19  can also be implemented using other edge region examples. 
     In some embodiments, a GDT/MOV device having one or more features as described herein, such as the examples of  FIGS. 4-18 , can be configured to provide symmetry or approximate symmetry about a mid-plane between first and second metal oxide layers or panels (for discrete or array-format processing). For example, given first and second metal oxide layers or panels can be dimensioned the same or approximately the same so as to provide such symmetry. Such symmetry or approximate symmetry can result in reduced mechanical stresses during various process steps, including steps involving temperature changes. 
     In some embodiments, a GDT/MOV device having one or more features as described herein can be combined with another device, including another GDT/MOV device. For example,  FIG. 20  shows that in some embodiments, two GDT/MOV devices can be implemented in series, in an integrated manner. More particularly, first and second GDT chambers  406 ,  414  are shown to be implemented in an alternating arrangement with first ( 402 ), second ( 410 ) and third ( 418 ) metal oxide layers. Thus, an electrode  404  can be a shared electrode for the first metal oxide layer  402  and the first GDT chamber  406 , an electrode  408  can be a shared electrode for the second metal oxide layer  410  and the first GDT chamber  406 , an electrode  412  can be a shared electrode for the second metal oxide layer  410  and the second GDT chamber  414 , and an electrode  416  can be a shared electrode for the third metal oxide layer  418  and the second GDT chamber  414 . 
     Electrodes  400  and  420  can be implemented as outer electrodes for the GDT/MOV device  100 . Accordingly, an electrical circuit representation of the structure of  FIG. 20  can be depicted as  102 . 
       FIGS. 21 and 22  show other examples where a GDT/MOV device can be combined with another electrical device. For example,  FIG. 21  shows that in some embodiments, a GDT/MOV device  100  having one or more features as described herein can be arranged in series with a thermal fuse  434  (e.g., a single flow thermal fuse), so as to provide an arrangement  430 . In some embodiments, the GDT/MOV device  100  can be in direct physical contact with the thermal fuse  434 . In some embodiments, the GDT/MOV device  100  can be electrically connected, but not in direct physical contact, with the thermal fuse  434 . 
     In another example,  FIG. 22  shows that in some embodiments, a GDT/MOV device  100  having one or more features as described herein can be arranged in series with a thermal switch  436  (e.g., a resettable thermal cutoff (TCO)), so as to provide an arrangement  432 . In some embodiments, the GDT/MOV device  100  can be in direct physical contact with the thermal switch  436 . In some embodiments, the GDT/MOV device  100  can be electrically connected, but not in direct physical contact, with the thermal switch  436 . 
     It will be understood that a GDT/MOV device having one or more features as described herein can also be implemented with one or more electrical components or device, in series, in parallel, or any combination thereof. 
     In some embodiments, MOV materials such as materials associated with the various metal oxide layers as described herein can include, for example, zinc oxide (ZnO) or ZnO-based material, and/or strontium titanate (SrTiO3) or SrTiO3-based material. In the context of the first example, a ZnO-based material can include or be formed by doping with other metal oxide compounds, such as Sb2O3, Bi2O3, MnO, Cr2O3, etc. 
     In some embodiments, an MOV material can include microstructure arrangement of metal oxides (e.g., ZnO particles) to provide a conduction mechanism. For example, a given ZnO particle or grain, which is generally semiconducting, can be separated from another ZnO grains by a thin insulating boundary layer. A breakdown voltage of such a boundary layer is approximately 3.2V. Thus, a given MOV device&#39;s breakdown voltage can be based on a number (e.g., an average number) of grains between two electrodes. 
     In some embodiments, some or all of the foregoing metal oxide layers can be implemented as a semiconducting ceramic material. With such a semiconducting ceramic layer, an outer electrode (e.g., configured as a terminal for mounting application) can be formed by first protecting the ceramic body before formation of the electrode (e.g., by plating). Such protecting of the ceramic body can be achieved by a formation of a passivation layer on the ceramic body utilizing chemical and/or physical application techniques. For example, a physical application technique can involve coating of the semiconducting ceramic body with some insulating polymer. In another example, a chemical application technique can involve a chemical reaction that results in an exposed surface of the semiconducting ceramic body becoming electrically insulating, at least for the purpose of formation of the electrode. 
     It is noted that at least the foregoing ZnO-based material and the SrTiO3-based material implemented as described herein generally do not include piezoelectric material and/or do not include piezoelectric property. Thus, in some embodiments, MOV materials such as materials associated with the various metal oxide layers as described herein, including some or all of the foregoing examples, can be configured to not have any significant amount of piezoelectric materials, and/or not have any significant amount of piezoelectric properties. In some embodiments, a GDT/MOV device having one or more features as described herein can include materials, such as materials associated with the various metal oxide layers as described herein, that are configured to not utilize any significant amount of piezoelectric property, even if present in small amounts. It will be understood that the foregoing piezoelectric properties can include, for example, a piezoresistivity property. 
     In some embodiments, spacer layers as described herein can include, for example, ceramic or alumina. 
     In some embodiments, various GDT chambers as described herein can be filled with, for example, neon, argon, nitrogen, and/or hydrogen. 
     In some embodiments, various inner or shared electrodes as described herein can be formed with, for example, silver, copper and/or tungsten. Formation of such electrodes can be achieved by, for example, screen printing, pad printing, or evaporation/photo-etch techniques; and some or all of such techniques can be followed by a sintering step. 
     In some embodiments, various outer electrodes as described herein can be formed with, for example, silver overplated with nickel or tin. Formation of such electrodes can be achieved by, for example, screen printing or pad printing techniques; and some or all of such techniques can be followed by a sintering step. 
     In some embodiments, various optional emissive coatings as described herein can be formed with, for example, various metals, salts and halide compounds. 
     Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” The word “coupled”, as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list. 
     The above detailed description of embodiments of the invention is not intended to be exhaustive or to limit the invention to the precise form disclosed above. While specific embodiments of, and examples for, the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. For example, while processes or blocks are presented in a given order, alternative embodiments may perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and/or modified. Each of these processes or blocks may be implemented in a variety of different ways. Also, while processes or blocks are at times shown as being performed in series, these processes or blocks may instead be performed in parallel, or may be performed at different times. 
     The teachings of the invention provided herein can be applied to other systems, not necessarily the system described above. The elements and acts of the various embodiments described above can be combined to provide further embodiments. 
     While some embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.