Electron emission device and electron emission display

An electron emission device includes a number of second electrodes intersected with a number of first electrodes to define a number of intersections. An electron emission unit is sandwiched between the first electrode and the second electrode at each of the number of intersections, wherein the electron emission unit includes a semiconductor layer, an electron collection layer, and an insulating layer stacked together, and the electron collection layer is a conductive layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims all benefits accruing under 35 U.S.C. §119 from China Patent Application 201410024482.4, filed on Jan. 20, 2014 in the China Intellectual Property Office, disclosure of which is incorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to an electron emission source, an electron emission device, and an electron emission display with the electron emission device, especially a cold cathode electron emission device with carbon nanotubes and the electron emission display with the same.

2. Description of Related Art

Electron emission display device is an integral part of the various vacuum electronics devices and equipment. In the field of display technology, electron emission display device can be widely used in automobiles, home audio-visual appliances, industrial equipment, and other fields.

Typically, the electron emission source in the electron emission display device has two types: hot cathode electron emission source and the cold cathode electron emission source. The cold cathode electron emission source comprises surface conduction electron-emitting source, field electron emission source, metal-insulator-metal (MIM) electron emission sources, and metal-insulator-semiconductor-metal (MISM) electron emission source, etc.

In MISM electron emission source, the electrons need to have sufficient electron average kinetic energy to escape through the upper electrode to a vacuum. However, in traditional MISM electron emission source, since the barrier is often higher than the average kinetic energy of electrons, the electron emission in the electron emission device is low, and the display effect of the electron emission display is not satisfied.

What is needed, therefore, is to provide an electron emission source, an electron emission device, and electron emission display that can overcome the above-described shortcomings.

DETAILED DESCRIPTION

Referring toFIG. 1, an electron emission source10of one embodiment comprises a first electrode101, a semiconductor layer102, an electron collection layer103, an insulating layer104, and a second electrode105stacked in that sequence. The first electrode101is spaced from the second electrode105. A surface of the first electrode101is an electron emission surface to emit electron.

Furthermore, the electron emission source10can be disposed on a substrate106, and the second electrode105is applied on a surface of the substrate106. The substrate106supports the electron emission source10. A material of the substrate106can glass, quartz, ceramics, diamond, silicon, or other hard plastic materials. The material of the substrate106can also be resins and other flexible materials. In one embodiment, the substrate106is silica.

The electron collection layer103is sandwiched between the insulating layer104and the semiconductor layer102. The first electrode101is located on the semiconductor layer102. The first electrode101is insulated from the second electrode105by the insulating layer104. The electron collection layer103collects and storage the electrons. The semiconductor layer102accelerates the electrons, thus the electrons can have enough energy to escape from the first electrode101.

A material of the insulating layer104can be a hard material such as aluminum oxide, silicon nitride, silicon oxide, or tantalum oxide. The material of the insulating layer104can also be a flexible material such as benzocyclobutene (BCB), acrylic resin, or polyester. A thickness of the insulating layer104can range from about 50 nanometers to 100 micrometers. In one embodiment, the insulating layer104is tantalum oxide with a thickness of 100 nanometers.

The semiconductor layer102is sandwiched between the first electrode101and the electron collection layer103. The semiconductor layer102plays a role of accelerating electrons. The electrons are accelerated in the semiconductor layer102. A material of the semiconductor layer102can be a semiconductor material, such as zinc sulfide, zinc oxide, magnesium zinc oxide, magnesium sulfide, cadmium sulfide, cadmium selenide, or zinc selenide. A thickness of the semiconductor layer102can range from about 3 nanometers to about 100 nanometers. In one embodiment, the material of the semiconductor layer102is zinc sulfide having a thickness of 50 nanometers.

The electron collection layer103is sandwiched between the semiconductor layer102and the insulating layer104. The electron collection layer103is a conductive layer comprising a conductive material. The material of the electron collection layer103can be gold, platinum, scandium, palladium, hafnium, or other metal or metal alloy. Furthermore, the material of the electron collection layer103can also be carbon nanotubes or graphene. A thickness of the electron collection layer103can range from about 10 nanometers to about 1 micrometer.

In one embodiment, the electron collection layer103can comprise a carbon nanotube layer. The carbon nanotube layer comprises a plurality of carbon nanotubes. The carbon nanotubes in the electron collection layer103extend parallel to the surface of the electron collection layer103.

The carbon nanotube layer includes a plurality of carbon nanotubes. The carbon nanotubes in the carbon nanotube layer can be single-walled, double-walled, or multi-walled carbon nanotubes. The length and diameter of the carbon nanotubes can be selected according to need. The thickness of the carbon nanotube layer can be in a range from about 10 nm to about 100 μm, for example, about 10 nm, 100 nm, 200 nm, 1 μm, 10 μm or 50 μm.

The carbon nanotube layer forms a pattern. The patterned carbon nanotube layer defines a plurality of apertures. The apertures can be dispersed uniformly. The apertures extend throughout the carbon nanotube layer along the thickness direction thereof. The aperture can be a hole defined by several adjacent carbon nanotubes, or a gap defined by two substantially parallel carbon nanotubes and extending along axial direction of the carbon nanotubes. The size of the aperture can be the diameter of the hole or width of the gap, and the average aperture size can be in a range from about 10 nm to about 500 μm, for example, about 50 nm, 100 nm, 500 nm, 1 μm, 10 μm, 80 μm or 120 μm. The hole-shaped apertures and the gap-shaped apertures can exist in the patterned carbon nanotube layer at the same time. The sizes of the apertures within the same carbon nanotube layer can be different. The smaller the size of the apertures, the less dislocation defects will occur during the process of growing first semiconductor layer120. In one embodiment, the sizes of the apertures are in a range from about 10 nm to about 10 μm.

The carbon nanotubes of the carbon nanotube layer can be orderly arranged to form an ordered carbon nanotube structure or disorderly arranged to form a disordered carbon nanotube structure. The term ‘disordered carbon nanotube structure’ includes, but is not limited to, a structure where the carbon nanotubes are arranged along many different directions, and the aligning directions of the carbon nanotubes are random. The number of the carbon nanotubes arranged along each different direction can be substantially the same (e.g. uniformly disordered). The disordered carbon nanotube structure can be isotropic. The carbon nanotubes in the disordered carbon nanotube structure can be entangled with each other. The term ‘ordered carbon nanotube structure’ includes, but is not limited to, a structure where the carbon nanotubes are arranged in a consistently systematic manner, e.g., the carbon nanotubes are arranged approximately along a same direction and/or have two or more sections within each of which the carbon nanotubes are arranged approximately along a same direction (different sections can have different directions).

In one embodiment, the carbon nanotubes in the carbon nanotube layer are arranged to extend along the direction substantially parallel to the surface of the semiconductor layer102. In one embodiment, all the carbon nanotubes in the carbon nanotube layer are arranged to extend along the same direction. In another embodiment, some of the carbon nanotubes in the carbon nanotube layer are arranged to extend along a first direction, and some of the carbon nanotubes in the carbon nanotube layer are arranged to extend along a second direction, perpendicular to the first direction.

In one embodiment, the carbon nanotube layer is a free-standing structure and can be drawn from a carbon nanotube array. The term “free-standing structure” means that the carbon nanotube layer can sustain the weight of itself when it is hoisted by a portion thereof without any significant damage to its structural integrity. Thus, the carbon nanotube layer can be suspended by two spaced supports. The free-standing carbon nanotube layer can be laid on the insulating layer104directly and easily.

The carbon nanotube layer can be a substantially pure structure of the carbon nanotubes, with few impurities and chemical functional groups. The carbon nanotube layer can be a composite including a carbon nanotube matrix and non-carbon nanotube materials. The non-carbon nanotube materials can be graphite, graphene, silicon carbide, boron nitride, silicon nitride, silicon dioxide, diamond, amorphous carbon, metal carbides, metal oxides, or metal nitrides. The non-carbon nanotube materials can be coated on the carbon nanotubes of the carbon nanotube layer or filled in the apertures. In one embodiment, the non-carbon nanotube materials are coated on the carbon nanotubes of the carbon nanotube layer so the carbon nanotubes can have a greater diameter and the apertures can a have smaller size. The non-carbon nanotube materials can be deposited on the carbon nanotubes of the carbon nanotube layer by CVD or physical vapor deposition (PVD), such as sputtering.

The carbon nanotube layer can include at least one carbon nanotube film, at least one carbon nanotube wire, or a combination thereof. In one embodiment, the carbon nanotube layer can include a single carbon nanotube film or two or more stacked carbon nanotube films. Thus, the thickness of the carbon nanotube layer can be controlled by the number of the stacked carbon nanotube films. The number of the stacked carbon nanotube films can be in a range from about 2 to about 100, for example, about 10, 30, or 50. In one embodiment, the carbon nanotube layer can include a layer of parallel and spaced carbon nanotube wires. The carbon nanotube layer can also include a plurality of carbon nanotube wires crossed or weaved together to form a carbon nanotube net. The distance between two adjacent parallel and spaced carbon nanotube wires can be in a range from about 0.1 μm to about 200 μm. In one embodiment, the distance between two adjacent parallel and spaced carbon nanotube wires can be in a range from about 10 μm to about 100 μm. The size of the apertures can be controlled by controlling the distance between two adjacent parallel and spaced carbon nanotube wires. The length of the gap between two adjacent parallel carbon nanotube wires can be equal to the length of the carbon nanotube wire. It is understood that any carbon nanotube structure described can be used with all embodiments.

In one embodiment, the carbon nanotube layer includes at least one drawn carbon nanotube film. A drawn carbon nanotube film can be drawn from a carbon nanotube array that is able to have a film drawn therefrom. The drawn carbon nanotube film includes a plurality of successive and oriented carbon nanotubes joined end-to-end by van der Waals attractive force therebetween. The drawn carbon nanotube film is a free-standing film. Referring toFIG. 2, each drawn carbon nanotube film includes a plurality of successively oriented carbon nanotube segments joined end-to-end by van der Waals attractive force therebetween. Each carbon nanotube segment includes a plurality of carbon nanotubes parallel to each other, and combined by van der Waals attractive force therebetween. Some variations can occur in the drawn carbon nanotube film. The carbon nanotubes in the drawn carbon nanotube film are oriented along a preferred orientation. The drawn carbon nanotube film can be treated with an organic solvent to increase the mechanical strength and toughness, and reduce the coefficient of friction of the drawn carbon nanotube film. A thickness of the drawn carbon nanotube film can range from about 0.5 nm to about 100 μm.

Referring toFIG. 3, the carbon nanotube layer can include at least two stacked drawn carbon nanotube films. In other embodiments, the carbon nanotube layer can include two or more coplanar carbon nanotube films, and each coplanar carbon nanotube film can include multiple layers. Additionally, if the carbon nanotubes in the carbon nanotube film are aligned along one preferred orientation (e.g., the drawn carbon nanotube film), an angle can exist between the orientation of carbon nanotubes in adjacent films, whether stacked or adjacent. Adjacent carbon nanotube films are combined by the van der Waals attractive force therebetween. An angle between the aligned directions of the carbon nanotubes in two adjacent carbon nanotube films can range from about 0 degrees to about 90 degrees. If the angle between the aligned directions of the carbon nanotubes in adjacent stacked drawn carbon nanotube films is larger than 0 degrees, a plurality of micropores is defined by the carbon nanotube layer. In one embodiment, the carbon nanotube layer shown with the angle between the aligned directions of the carbon nanotubes in adjacent stacked drawn carbon nanotube films is 90 degrees. Stacking the carbon nanotube films will also add to the structural integrity of the carbon nanotube layer.

The carbon nanotube wire can be untwisted or twisted. Treating the drawn carbon nanotube film with a volatile organic solvent can form the untwisted carbon nanotube wire. Specifically, the organic solvent is applied to soak the entire surface of the drawn carbon nanotube film. During the soaking, adjacent parallel carbon nanotubes in the drawn carbon nanotube film will bundle together, due to the surface tension of the organic solvent as it volatilizes. Thus, the drawn carbon nanotube film will be shrunk into untwisted carbon nanotube wire. Referring toFIG. 4, the untwisted carbon nanotube wire includes a plurality of carbon nanotubes substantially oriented along a same direction (i.e., a direction along the length of the untwisted carbon nanotube wire). The carbon nanotubes are parallel to the axis of the untwisted carbon nanotube wire. Specifically, the untwisted carbon nanotube wire includes a plurality of successive carbon nanotube segments joined end to end by van der Waals attractive force therebetween. Each carbon nanotube segment includes a plurality of carbon nanotubes substantially parallel to each other, and combined by van der Waals attractive force therebetween. The carbon nanotube segments can vary in width, thickness, uniformity, and shape. Length of the untwisted carbon nanotube wire can be arbitrarily set as desired. A diameter of the untwisted carbon nanotube wire ranges from about 0.5 nm to about 100 μm.

The twisted carbon nanotube wire can be formed by twisting a drawn carbon nanotube film using a mechanical force to turn the two ends of the drawn carbon nanotube film in opposite directions. Referring toFIG. 5, the twisted carbon nanotube wire includes a plurality of carbon nanotubes helically oriented around an axial direction of the twisted carbon nanotube wire. Specifically, the twisted carbon nanotube wire includes a plurality of successive carbon nanotube segments joined end to end by van der Waals attractive force therebetween. Each carbon nanotube segment includes a plurality of carbon nanotubes parallel to each other, and combined by van der Waals attractive force therebetween. Length of the carbon nanotube wire can be set as desired. A diameter of the twisted carbon nanotube wire can be from about 0.5 nm to about 100 μm. Further, the twisted carbon nanotube wire can be treated with a volatile organic solvent after being twisted. After being soaked by the organic solvent, the adjacent paralleled carbon nanotubes in the twisted carbon nanotube wire will bundle together, due to the surface tension of the organic solvent when the organic solvent volatilizes. The specific surface area of the twisted carbon nanotube wire will decrease, while the density and strength of the twisted carbon nanotube wire will be increased.

The electron collection layer103can also be a graphene layer. The graphene layer can include at least one graphene film. The graphene film, namely a single-layer graphene, is a single layer of continuous carbon atoms. The single-layer graphene is a nanometer-thick two-dimensional analog of fullerenes and carbon nanotubes. When the graphene layer includes the at least one graphene film, a plurality of graphene films can be stacked on each other or arranged coplanar side by side. The thickness of the graphene layer can be in a range from about 0.34 nanometers to about 10 micrometers. For example, the thickness of the graphene layer can be 1 nanometer, 10 nanometers, 200 nanometers, 1 micrometer, or 10 micrometers. The single-layer graphene can have a thickness of a single carbon atom. In one embodiment, the graphene layer is a pure graphene structure consisting of graphene. Because the single-layer graphene has great conductivity, thus the electrons can be easily collected and accelerated to the semiconductor layer102.

The graphene layer can be prepared and transferred to the substrate by graphene powder or graphene film. The graphene film can also be prepared by the method of chemical vapor deposition (CVD) method, a mechanical peeling method, electrostatic deposition method, a silicon carbide (SiC) pyrolysis, or epitaxial growth method. The graphene powder can prepared by liquid phase separation method, intercalation stripping method, cutting carbon nanotubes, preparation solvothermal method, or organic synthesis method.

In one embodiment, the electron collection layer103is a drawn carbon nanotube film having a thickness of 5 nanometers to 50 nanometers. The carbon nanotube film has good tensile conductivity and electron collecting effect. Furthermore, the carbon nanotube film has good mechanical properties, which can effectively improve the lifespan of the electron emission source10.

The first electrode101is a thin conductive metal film. A material of the first electrode101can be gold, platinum, scandium, palladium, or hafnium metal. The thickness of the first electrode101can range from about 10 nanometers to about 100 micrometers, such as 10 nanometers, 50 nanometers. In one embodiment, the first electrode101is molybdenum film having a thickness of 100 nanometers. Furthermore, the material of the first electrode101may also be carbon nanotube layer or graphene layer. The plurality of carbon nanotubes in the carbon nanotube layer form a conductive network. The carbon nanotube layer can also define a plurality of apertures. Thus the electrons can be easily escaped from the first electrode101. The material of the second electrode105can be same as the first electrode101.

The electron emission source10works in the alternating current (AC) driving mode. The working principle of the electron emission source10is: in the negative half cycle, the potential of the second electrode105is high, and the electrons are injected into the semiconductor layer102from the first electrode101. While the electrons reach the electron collection layer103, the electrons will be collected and stored in the electron collection layer103. An interface between the electron collection layer103and insulating layer104forms an interface state. In the positive half cycle, due to the higher potential of the carbon nanotube layer of the first electrode101, the electrons stored on the interface state are pulled to the semiconductor layer102and accelerated in the semiconductor layer102. Because the semiconductor layer102is in contact with the first electrode101, a part of high-energy electrons can rapidly pass through the carbon nanotube layer of the first electrode101.

Referring toFIG. 6, a method of making electron emission source10comprises:

(S11) locating a second electrode105on a surface of a substrate106;

(S12) depositing an insulating layer104on the second electrode105;

(S13) applying an electron collection layer103on the insulating layer104;

(S14) locating a semiconductor layer102on the electron collection layer103; and

(S15) applying a first electrode101on the semiconductor layer102.

In step (S11), the substrate106can be rectangular. The material of the substrate106can be insulating material such as glass, ceramic, or silicon dioxide. In one embodiment, the substrate106is a silicon dioxide.

The preparation method of the second electrode105can be magnetron sputtering method, vapor deposition method, or an atomic layer deposition method. In one embodiment, the second electrode105is the molybdenum metal film formed by vapor deposition, and the thickness of the second electrode105is about 100 nanometers.

In step (S12), the preparation method of the insulating layer104can be the magnetron sputtering method, the vapor deposition method, or the atomic layer deposition method. In one embodiment, the insulating layer104is tantalum oxide formed by atomic layer deposition method, and the thickness of the insulating layer104is about 100 nanometers.

In step (S13), the method of forming the electron collector layer103can be selected according to the material. While the material of the electron collector layer103is metal or metal alloy, the electron collection layer103can be formed by magnetron sputtering, vapor deposition, or atomic layer deposition. While the electron collector layer103comprises carbon nanotube layer, the electron collection layer103can be formed by directly locating a drawn carbon nanotube film, a flocculate carbon nanotube film, or a pressed carbon nanotube film on the insulating layer104. While the material of the electron collector layer103is graphene, the electron collection layer103can be formed by applying a graphene layer on the insulating layer104. In one embodiment, the electron collection layer103is formed by directly locating a carbon nanotube film drawn from a carbon nanotube array. The thickness of the electron collector layer103ranges from about 5 nanometers to about 50 nanometers.

In step (S14), the method of forming semiconductor layer102can be similar to the method of forming the insulating layer104. In one embodiment, the semiconductor layer102is zinc sulfide layer formed by a vapor deposition method, and the thickness of the semiconductor layer102is about 50 nanometers.

In step (S15), the method of forming the first electrode101can be same as the method of forming the electron collection layer103. In one embodiment, the drawn carbon nanotube film is applied as the first electrode101.

The electron emission source10can have the following advantages. The electron collection layer103is located between the semiconductor layer102and the insulating layer104, thus the electron collection layer103can effectively collect and store the electrons between the semiconductor layer102and the insulating layer104, and the electron emission efficiency of the electron emission source10can be improved compared to the traditional MISM electron emission source.

Referring toFIG. 7, an electron emission source20of one embodiment comprises a first electrode101, a semiconductor layer102, an electron collection layer103, an insulating layer104, and a second electrode105stacked in that sequence. Furthermore, a pair of bus electrodes107is located on the first electrode101.

The structure of electron emission source20is similar to the structure of electron emission source10, except that the pair of bus electrodes107is located on the first electrode101.

The pair of bus electrodes107are spaced from each other and electrically connected to the first electrode101in order to supply current. Each bus electrode107is a bar-shaped electrode.

While the first electrode101comprises the plurality of carbon nanotubes, the pair of bus electrodes107can be applied on the two opposite sides of the first electrode101along the extending direction of the carbon nanotubes. The extending direction of the bar-shaped bus electrode107is perpendicular to the extending direction of the plurality of carbon nanotubes of the first electrode101. Thus the current can be uniformly distributed in the first electrode101.

A shape of the bus electrode107can be bar-shaped, square, triangular, rectangular, etc. A material of the bus electrode107can be gold, platinum, scandium, palladium, hafnium, or metal alloy. In one embodiment, the bus electrode107is bar-shaped platinum electrode. The pair of bar-shaped bus electrodes107are parallel with and spaced from each other.

Referring toFIG. 8, an electron emission device300of one embodiment comprises a plurality of electron emission units30. Each of the plurality of electron emission units30comprises a first electrode101, a semiconductor layer102, an electron collection layer103, an insulating layer104, and a second electrode105stacked in that sequence. The insulating layers104in the plurality of electron emission units30are in contact with each other and form a continuous layer. The electron emission device300can be located on a substrate106.

The electron emission unit30is similar to the electron emission source structure10described above, except that the plurality of electron emission units30share the common insulating layer104. The plurality of electron emission units30can work independently from each other. In detail, the first electrodes101in adjacent two of the plurality of electron emission units30are spaced apart from each other, the semiconductor layers102in adjacent two of the plurality of electron emission units30are spaced apart from each other, and the second electrodes105in adjacent two of the plurality of electron emission units30are also spaced apart from each other. In one embodiment, a distance between adjacent two semiconductor layers102is about 200 nanometers, a distance between adjacent two first electrodes101is about 200 nanometers, and a distance between the adjacent two electrodes105is about 200 nanometers.

An embodiment of a method of making electron emission device300comprises:

(S21) locating a plurality of second electrodes105on a surface of a substrate106, wherein the plurality of second electrodes105are spaced from each other;

(S22) depositing an insulating layer104on the plurality of second electrodes105;

(S23) applying an electron collection layer103on the insulating layer104;

(S24) forming a plurality of semiconductor layer102by locating a semiconductor layer preform on the electron collection layer103and patterning the semiconductor layer preform; and

(S25) applying a plurality of first electrodes101on the plurality of semiconductor layer102.

The method of making the electron emission device300is similar to the method of making the electron emission source10, except that the plurality of second electrodes105is applied on the substrate106and spaced from each other.

In step (S21), the method of forming the plurality of second electrodes105can be screen printing method, magnetron sputtering method, vapor deposition method, atomic layer deposition method. In one embodiment, the plurality of second electrodes105are formed via the vapor deposition method comprising:

providing a mask layer having a plurality of openings;

deposing a conductive layer on the mask layer; and

removing the mask layer.

The material of the mask layer can be polymethyl methacrylate (PMMA) or silicone compound (HSQ). The size and the position of the openings in the mask layer can be selected according to the requirement of the distribution of the plurality of electron emitting units30. In one embodiment, the material of the second electrode105is molybdenum. The number of the second electrode105is 16, and the number of the electron emission unit30is also 16.

In step (S25), the method for forming the first electrode101can be selected according to the material of the first electrode101. While the material of the first electrode101is conductive metal, the first electrode can be formed by sputtering, atomic layer deposition, vapor deposition method. While the first electrode101is graphene or carbon nanotubes, the first electrode101can be formed by chemical vapor deposition. The carbon nanotube layer or graphene membrane is etched to form the first electrodes101spaced apart.

In step (S24), the semiconductor layer preform can be patterned via plasma etching, laser etching, or wet etching. In one embodiment, the semiconductor layer preform is patterned according to the distribution of the first electrode101. Thus each of the plurality of electron emission units30comprises one electrode101, one semiconductor layer102, and one second electrode105.

Furthermore, the electron collection layer103can also be patterned. Thus the first electrode101, the semiconductor layer102, the electron collection layer103, and the second electrode105in the plurality of electron emission units30are spaced from each other. The plurality of electron emission units30share common insulating layer104. The electron collection layer103can be patterned by plasma etching method, laser etching method, or wet etching method.

Referring toFIGS. 9-10, an electron emission device400of one embodiment comprises a plurality of electron emission units40, a plurality of row electrodes401, and a plurality of column electrodes402on a substrate106. Each of the plurality of electron emission units40comprises a first electrode101, a semiconductor layer102, an electron collection layer103, an insulating layer104, and a second electrode105stacked in that sequence. The insulating layers104in the plurality of electron emission units40are connected with each other to form a continuous layered structure.

The electron emission device400is similar to the electron emission device300, except that the electron emission device400further comprises the plurality of row electrodes401and the plurality of column electrodes402electrically connected to the plurality of electron emission units40.

The plurality of row electrodes401is parallel with and spaced from each other. Similarly, the plurality of column electrodes402are parallel with and spaced from each other. The plurality of column electrodes402are insulated from the plurality of row electrodes402through the insulating layer104. The adjacent two row electrodes401are intersected with the adjacent two row electrodes401to form a grid.

A section is defined between the adjacent two row electrodes401and the adjacent two column electrodes402. The electron emission unit40is received in one of sections and electrically connected to the row electrode401and the column electrode402. The row electrode401and the column electrode402can electrically connect to the electron emission unit40via two electrode leads403respectively to supply current for the electron emission unit40.

In one embodiment, the plurality of column electrodes402are perpendicular to the plurality of row electrodes401.

The plurality of electron emission units40form an array with a plurality of rows and columns. The plurality of first electrodes101in the plurality of electron emission units40are spaced apart from each other. The plurality of second electrodes105in the plurality of electron emission units40are also spaced apart from each other. The plurality of semiconductor layers102in the plurality of electron emission units40can be spaced apart from each other.

In one embodiment, the plurality of electron collection layer103in the plurality of electron emission units40can connect to each other to form an integrated structure. It means that the plurality of electron collection layer103form a continuous layered structure, and the plurality of electron emission units40share a common electron collection layer103.

Referring toFIG. 11, an electron emission display500of one embodiment comprises a substrate106, a plurality of electron emission units40on the substrate106, and an anode structure510. The plurality of electron emission units40are spaced from the anode structure510and face to the anode structure510.

The anode structure510comprises a glass substrate512, an anode514on the glass substrate512, and phosphor layer516coated on the anode514. The anode structure510is supported by an insulating support518. The substrate106, the glass substrate512, and the insulating support518form a sealed space. The anode514can be indium tin oxide (ITO) film. The phosphor layer516face to the plurality of electron emission units40.

In detail, the phosphor layer516face to the first electrode101to receive electrons emitted from the first electrode101. In application, different voltages are applied to the first electrode101, the second electrode105, and the anode514of the electron emission display500. In one embodiment, the second electrode105is at the ground or zero voltage, the voltage applied on the first electrode101is several tens of volts, and the voltage applied on the anode514is a few hundred volts. The electrons emitted from the first electrode101of the electron emission unit40are driven under the electric filed to move toward the phosphor layer516. The electrons eventually reaches the anode structure510and bombarded the phosphor layer516coated on the anode514. Thus fluorescence can be activated from the phosphor layer516. Referring toFIG. 12, the electrons in the electron emission display500are uniformly emitted, and the electron emission display500has better luminous intensity.

Referring toFIGS. 13 and 14, an electron emission device600of one embodiment comprises a plurality of first electrodes1010spaced from each other, a plurality of second electrodes1050spaced from each other. The plurality of first electrodes1010are bar-shaped and extend along a first direction, and the plurality of second electrodes1050are bar-shaped and extend along a second direction that intersects with the first direction. The plurality of first electrodes1010are intersected with the plurality of second electrodes1050. A semiconductor layer102, an electron collection layer103, and an insulating layer104are stacked together and sandwiched between the first electrode1010and the second electrode1050at intersections of the first electrode1010and the second electrode1050. The first electrode1010is located on the semiconductor layer102.

The electron emission device600is similar to the electron emission device400, except that the electron emission device600comprises the plurality of bar-shaped first electrodes1010and the plurality of bar-shaped second electrodes1050.

The first direction can be defined as the X direction, and the second direction can be defined as the Y direction that intersects with the X direction. The Z direction is defined as a third direction perpendicular to both the X direction and Y direction. The plurality of first electrodes1010are aligned along a plurality of rows, and the plurality of second electrodes1050are aligned along a plurality of columns. Thus the plurality of first electrodes1010and the plurality of second electrodes1050are overlapped with each other at the plurality of intersections. An electron emission unit60is formed at each intersection in the electron emission device600. The electron emission unit60comprises the semiconductor layer102, the electron collection layer103, and the insulating layer104sandwiched between the first electrode1010and the second electrode1050at the intersection, and the semiconductor layer102is in contact with the first electrode1010.

The plurality of electron emission units60can be spaced from each other and aligned along a plurality of rows and a plurality of columns. The semiconductor layers102in the plurality of electron emission units60are also spaced apart from each other. The plurality of semiconductor layers102aligned along the same row are electrically connected to the same first electrode101. The plurality of semiconductor layers102aligned along the same column are electrically connected to the same second electrode105. Thus the plurality of electron emission units60aligned along the same rows share the same first electrode101, and the plurality of electron emission units60aligned along the same columns share the same second electrode105.

Furthermore, the plurality of electron emission units60can share a common electron collection layer103. The plurality of electron emission units60can also share a common insulating layer104. In one embodiment, the electron collection layer103in the plurality of electron emission units60are spaced apart from each other, and the insulating layer104in the plurality of electron emission units60are also spaced apart from each other.

While a voltage is applied between the first electrode1010and the second electrode1050, the electrons can be emitted from each of the plurality of electron emission units60at the intersections.

In application, different voltages can be applied to the first electrode1010, the second electrode1050, and the anode514. The second electrode1050can be applied with a ground or zero voltage, the voltage applied on the first electrode1010can be tens of volts to hundreds of volts. An electric field is formed between the first electrode1010and the second electrode1050at the intersection. The electrons pass through the semiconductor layer102and emit from the first electrode1010.

An embodiment of a method of making electron emission device600comprises:

(S31) forming a plurality of second electrodes1050on a surface of a substrate106, wherein the plurality of second electrodes1050are spaced from each other and extend along a first direction;

(S32) depositing an insulating layer104on the plurality of second electrodes1050;

(S33) applying an electron collection layer103on the insulating layer104;

(S34) forming a plurality of semiconductor layers102by locating a semiconductor preform on the electron collection layer103and patterning the semiconductor layer preform; and

(S25) applying a plurality of first electrodes1010on the plurality of semiconductor layer102according to the plurality of second electrodes105, wherein the plurality of first electrodes1010are spaced from each other and extend along a second direction.

The method of making electron emission device600in present embodiment is similar to the method of making electron emission device300. The first direction can be intersected with the second direction.

Furthermore, the electron collection layer103and the insulating layer104can also be patterned according the patterned structure of the first electrode1010.

Referring toFIG. 15, an electron emission display700of one embodiment comprises a substrate106, an electron emission device600located on the substrate106, and an anode structure510spaced from the electron emission device600. The electron emission device600comprises a plurality of electron emission units60.

The electron emission display700is similar to the electron emission display500, except that the plurality of first electrodes101are connected with each other to form a plurality of bar-shaped first electrodes1010along a first direction. Furthermore, the plurality of second electrodes105are connected with each other to form the plurality of second electrodes1050along a second direction.

The electrons emitted from the surface of the first electrodes1010at the intersection and bombard the phosphor layer516coated on the anode514. Thus fluorescence is generated from the electron emission display700.

It is to be understood that the above-described embodiments are intended to illustrate rather than limit the disclosure. Variations may be made to the embodiments without departing from the spirit of the disclosure as claimed. It is understood that any element of any one embodiment is considered to be disclosed to be incorporated with any other embodiment. The above-described embodiments illustrate the scope of the disclosure but do not restrict the scope of the disclosure.