Patent Description:
A light emitting diode (LED) is a semiconductor light source that emits visible light when current flows through it. LEDs combine a P-type semiconductor with an N-type semiconductor. LEDs commonly use a III-group compound semiconductor. A III-group compound semiconductor provides stable operation at a higher temperature than devices that use other semiconductors. The III-group compound is typically formed on a substrate formed of sapphire or silicon carbide (SiC).

The projection of light requires a module with many small LEDs packed closely together. In some applications, it is desirable to place LEDs of different colors closely together in the same module, or even to have one LED emit different colors. This capability could, for example, allow brake indicator (red) and turn indicator (amber) functionality to be integrated into one compact module, taking up less space in an automobile. In the future, there may be a desire for vehicles to project light of different colors onto the road or sidewalk to communicate with pedestrians or other vehicles.

Compact integration of LEDs based on standard AlInGaP red and amber emitters is difficult because different wafers must be used for each color, and the response of LED efficiency to changes in temperature is very different for the different colors. Additionally, using a standard InGaN LED and changing the drive current results in amber light (high current density) of much higher luminance than red light (low current density). Many applications require red light of similar luminance as amber light. For example, both the brake and turn signals of an automobile have to be bright enough to be visible in sunshine. Accordingly, there is a need for LEDs that are able to produce different colors of light but with similar luminance levels.

<CIT> describes a light emitting device according including a first light emitting cell, a second light emitting cell, and a third light emitting cell each including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer, pads electrically connected to the first to third light emitting cells to independently drive the first to third light emitting cells, a second wavelength converter for converting a wavelength of a light emitted from the second light emitting cell, and a third wavelength converter for converting a wavelength of a light emitted from the third light emitting cell, the third wavelength converter converts the wavelength of the light into a longer wavelength than the second wavelength converter, the second light emitting cell has a larger area than the first light emitting cell, and the third light emitting cell has a larger area than the second light emitting cell.

<CIT> describes an optoelectronic semiconductor chip comprising a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, a first and a second current distribution layer, and a first and a second contact element. The first and second semiconductor layers form a layer stack. The first current distribution layer is situated on a side of the first semiconductor layer facing away from the second semiconductor layer and is electrically conductively connected to the first semiconductor layer. The second current distribution layer is situated on the side of the first semiconductor layer facing away from the second semiconductor layer and is electrically conductively connected to the second semiconductor layer. The first contact element is connected to the first current distribution layer. The second contact element is connected to the second current distribution layer.

Embodiments of the disclosure are directed to LED devices and methods for manufacturing LED devices. In a first embodiment, a light emitting diode (LED) device comprises a mesa comprising semiconductor layers, the semiconductor layers including an n-type layer, an active layer, and a p-type layer; an anode contact comprising a first anode region and a second anode region separated by a gap, the first anode region on a top surface of the mesa, the second anode region adjacent the first anode region; a switch connecting the first anode region and the second anode region; and a cathode contact adjacent the anode contact and in electrical communication with the n-type layer.

In a second embodiment, the first embodiment is modified so that the first anode region has a first area and the second anode region has a second area, the second area larger than the first area. In a third embodiment, the first embodiment is modified so that gap has a width greater than about <NUM> micron.

In a fourth embodiment, the third embodiment further includes a feature that there is a first dielectric layer in the gap. In a fifth embodiment, the fourth embodiment further includes a feature that there is a second dielectric layer on a top surface of the anode contact, and a mirror layer on a top surface of the first dielectric layer. In a sixth embodiment, the fifth embodiment is modified so that the first dielectric layer and the second dielectric layer independently comprise one or more of silicon oxide (SiO<NUM>), aluminum oxide (Al<NUM>O<NUM>), silicon nitride (SiNx), titanium oxide (TiO<NUM>), niobium oxide (Nb<NUM>O<NUM>), zirconium oxide (ZrO<NUM>), and hafnium oxide (HfO<NUM>). In a seventh embodiment, the fifth embodiment further includes a feature that the mirror layer comprises one or more of aluminum (Al), silver (Ag), gold (Au), copper (Cu), metallic nitrides and alloys thereof.

In an eighth embodiment, the first embodiment is modified so that the first anode region and the second anode region independently comprise a material selected from one or more of silver (Ag), indium tin oxide (ITO), nickel (Ni), palladium (Pd), platinum (Pt), and zinc oxide (ZnO). In a ninth embodiment, the first embodiment further includes the feature of an anode terminal on the anode contact, a cathode terminal on the cathode contact, and a switch terminal on the switch.

Another aspect of the disclosure pertains to a method of operating the LED device of the first embodiment. In a tenth embodiment, the method comprises opening the switch and flowing a current through the anode contact to the first anode region to emit light having a centroid wavelength less than <NUM>. In an eleventh embodiment, the method comprises closing the switch, and flowing a current through the anode contact to the first anode region and to the second anode region to emit light having a centroid wavelength greater than <NUM>.

Another aspect of the disclosure pertains to a light emitting diode (LED) device. In a twelfth embodiment, a light emitting diode (LED) device comprises a mesa array comprising a first mesa and a second mesa separated by a trench, the first mesa and the second mesa comprising semiconductor layers, the semiconductor layers including an n-type layer, an active layer, and a p-type layer, the trench having at least one side wall and extending to the n-type layer, the first mesa having a first width and the second mesa having a second width, the first width greater than the second width. A first anode contact is on a top surface of the first mesa. A second anode contact is on a top surface of the second mesa, and a cathode contact is adjacent the first mesa and adjacent the second mesa. In a thirteenth embodiment, the twelfth embodied is modified so that the first anode contact and the second anode contact independently comprise a material selected from one or more of silver (Ag), indium tin oxide (ITO), nickel (Ni), palladium (Pd), platinum (Pt), and zinc oxide (ZnO). In a fourteenth embodiment, the twelfth embodiment further includes the feature of a first anode terminal on the first anode contact, a second anode terminal on the second anode contact, and a cathode terminal on the cathode contact. In a fifteenth embodiment, the twelfth embodiment further includes the feature of a dielectric layer on the at least one sidewall of the trench. In a sixteenth embodiment, the fifteenth embodiment is modified so that the dielectric layer comprises one or more of silicon oxide (SiO<NUM>), aluminum oxide (Al<NUM>O<NUM>), silicon nitride (SiNx), titanium oxide (TiO<NUM>), niobium oxide (Nb<NUM>O<NUM>), zirconium oxide (ZrO<NUM>), and hafnium oxide (HfO<NUM>).

Another aspect of the disclosure pertains to a method of operating the LED device of the twelfth embodiment. In a seventeenth embodiment, the method comprises flowing a current through the first anode contact to emit light having a centroid wavelength less than <NUM>. In an eighteenth embodiment, the method comprises flowing a current through the second anode contact to emit light having a centroid wavelength greater than <NUM>.

A further aspect of the disclosure pertains to a light emitting diode (LED) device. In a nineteenth embodiment, a light emitting diode (LED) device comprises a first mesa array comprising a plurality of first mesas separated by a first trench, the first trench filled with a dielectric layer; a second mesa array comprising a plurality of second mesas separated by a second trench, the second trench filled with a dielectric layer; a first anode contact on a top surface of the first mesa array; a second anode contact on a top surface of the second mesa array; and a cathode contact adjacent to the first mesa array and the second mesa array. The plurality of first mesas and the plurality of second mesas comprise semiconductor layers. The semiconductor layers include an n-type layer, an active layer, and a p-type layer, and the first trench and the second trench extend to the n-type layer. In a twentieth embodiment, the nineteenth embodiment is modified so that the first anode contact and the second anode contact independently comprise a material selected from one or more of silver (Ag), indium tin oxide (ITO), nickel (Ni), palladium (Pd), platinum (Pt), and zinc oxide (ZnO). In a twenty-first embodiment, further includes the feature of a first anode terminal on the first anode contact, a second anode terminal on the second anode contact, and a cathode terminal on the cathode contact. In a twenty-second embodiment, the nineteenth embodiment is modified so that the dielectric layer comprises one or more of silicon oxide (SiO<NUM>), aluminum oxide (Al<NUM>O<NUM>), silicon nitride (SiNx), titanium oxide (TiO<NUM>), niobium oxide (Nb<NUM>O<NUM>), zirconium oxide (ZrO<NUM>), and hafnium oxide (HfO<NUM>).

Another aspect of the disclosure pertains to a method of operating the LED device of the nineteenth embodiment. In a twenty-third embodiment, the method comprises flowing a current through the first anode contact to emit light having a centroid wavelength less than <NUM>. In twenty-fourth embodiment, the method comprises flowing a current through the second anode contact to emit light having a centroid wavelength greater than <NUM>.

This disclosure comprises embodiments, some of which are embodiments of the invention as defined by the appended claims.

Before describing several exemplary embodiments of the disclosure, it is to be understood that the disclosure is not limited to the details of construction or process steps set forth in the following description. The disclosure is capable of other embodiments and of being practiced or being carried out in various ways.

The term "substrate" as used herein according to one or more embodiments refers to a structure, intermediate or final, having a surface, or portion of a surface, upon which a process acts. In addition, reference to a substrate in some embodiments also refers to only a portion of the substrate, unless the context clearly indicates otherwise. Further, reference to depositing on a substrate according to some embodiments includes depositing on a bare substrate or on a substrate with one or more layers, films, features or materials deposited or formed thereon.

In one or more embodiments, the "substrate" means any substrate or material surface formed on a substrate upon which film processing is performed during a fabrication process. In exemplary embodiments, a substrate surface on which processing is performed includes materials such as silicon, silicon oxide, silicon on insulator (SOI), strained silicon, amorphous silicon, doped silicon, carbon doped silicon oxides, germanium, gallium arsenide, glass, sapphire, and any other suitable materials such as metals, metal nitrides, III-nitrides (e.g., GaN, AlN, InN and other alloys), metal alloys, and other conductive materials, depending on the application. Substrates include, without limitation, light emitting diode (LED) devices. Substrates in some embodiments are exposed to a pretreatment process to polish, etch, reduce, oxidize, hydroxylate, anneal, UV cure, e-beam cure and/or bake the substrate surface. In addition to film processing directly on the surface of the substrate itself, in some embodiments, any of the film processing steps disclosed is also performed on an underlayer formed on the substrate, and the term "substrate surface" is intended to include such underlayer as the context indicates. Thus for example, where a film/layer or partial film/layer has been deposited onto a substrate surface, the exposed surface of the newly deposited film/layer becomes the substrate surface.

The term "wafer" and "substrate" will be used interchangeably in the instant disclosure. Thus, as used herein, a wafer serves as the substrate for the formation of the LED devices described herein.

Embodiments described herein describe LED devices and methods for forming LED devices. In particular, the present disclosure describes LED devices and methods to produce LED devices which advantageously emit multiple colors or wavelengths from a single wafer. The LED devices allow light of similar luminance levels to be emitted for different driving current densities. One or more embodiments of the disclosure can be used in the fabrication of microLED displays.

In one or embodiments, provided is a gallium nitride (GaN)-based LED wafer containing InGaN quantum wells, which emits light having a centroid wavelength greater than <NUM> for a sufficiently low current density and emits light having a centroid wavelength less than <NUM> for larger current densities.

In one or more embodiments, a pulsed current source is used to drive the LED. In one or more embodiments, the duty cycle of the current source is controlled in addition to the current. In one or more embodiments, light having a centroid wavelength less than <NUM> of similar time-averaged radiance as light having a centroid wavelength greater than <NUM> is obtained by increasing the current while decreasing the duty cycle. In one or more embodiments, pulse frequency is set high enough so that intensity modulation from individual pulses is not visible.

In one or more embodiments, a pulsed voltage source is used to drive the LED. In one or more embodiments, the duty cycle of the voltage source is controlled in addition to the voltage. In one or more embodiments, light having a centroid wavelength less than <NUM> of similar time-averaged radiance as light having a centroid wavelength greater than <NUM> is obtained by increasing the voltage while decreasing the duty cycle. In one or more embodiments, pulse frequency is set high enough so that intensity modulation from individual pulses is not visible.

In one or more embodiments, the LED includes an integrated switch that increases the anode contact area when the LED is operated in an emitting mode where the centroid wavelength greater than <NUM>. In one or more embodiments, the increase in contact area is designed to shift the color from light having a centroid wavelength less than <NUM> to light having a centroid wavelength greater than <NUM> when the LED is operated at fixed dc current.

In one or more embodiments, the LED wafer is divided into two arrays of pixels with equal numbers of pixels of different sizes in each array. Two separate anode contacts are provided (one for each array). The array with larger pixel size emits light having a centroid wavelength greater than <NUM>, and the array with smaller pixel size emits light having a centroid wavelength less than <NUM>. In one or more embodiments, the two arrays can be driven with the same current supply or different current supplies. In some embodiments, the two arrays can be driven by a fixed DC current supply.

In one or more embodiments, the LED wafer is divided into two arrays of pixels with different numbers of pixels of equal sizes in each array. Two separate anode contacts are provided (one for each array). In one or more embodiments, the array with more pixels emits light having a centroid wavelength greater than <NUM>. In one or more embodiments, the array with fewer pixels emits light having a centroid wavelength less than <NUM>. The two arrays can be driven with the same current supply or different ones. The array with more pixels emits light having a centroid wavelength greater than <NUM>, and the array with fewer pixels emits light having a centroid wavelength less than <NUM>. In one or more embodiments, the two arrays can be driven with the same current supply or different current supplies. In some embodiments, the two arrays can be driven by a fixed DC current supply.

<FIG> illustrates a top view of an LED device according to one or more embodiments of the present invention. <FIG> illustrates a cross-sectional view taken alone line A-A' of the LED device of <FIG>. Referring to <FIG>, in one or more embodiments semiconductor layers <NUM> are grown on a substrate <NUM>. The semiconductor layers <NUM> according to one or more embodiments comprise epitaxial layers, III-nitride layers or epitaxial III-nitride layers. In one or more embodiments, the semiconductor layers are epitaxial semiconductor layers having a thickness at least <NUM> micron.

The substrate <NUM> may be any substrate known to one of skill in the art. In one or more embodiments, the substrate <NUM> comprises one or more of sapphire, silicon carbide, silicon (Si), quartz, magnesium oxide (MgO), zinc oxide (ZnO), spinel, and the like. In one or more embodiments, the substrate <NUM> is not patterned prior to the growth of the Epi-layer. Thus, in some embodiments, the substrate <NUM> is not patterned and can be considered to be flat or substantially flat. In other embodiments, the substrate is patterned, e.g. patterned sapphire substrate (PSS).

In one or more embodiments, the semiconductor layers <NUM> comprise a III-nitride material, and in specific embodiments epitaxial III-nitride material. In some embodiments, the III-nitride material comprises one or more of gallium (Ga), aluminum (Al), and indium (In). Thus, in some embodiments, the semiconductor layers <NUM> comprises one or more of gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN), aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), indium aluminum nitride (InAlN), aluminum indium gallium nitride (AlInGaN) and the like. In one or more specific embodiments, the semiconductor layers <NUM> comprise a p-type layer <NUM>, an active region <NUM>, and an n-type layer <NUM>. In specific embodiments, the n-type layer <NUM> and p-type layer <NUM> of the LED comprise n-doped and p-doped GaN.

In one or more embodiments, the layers of III-nitride material which form the LED are deposited by one or more of sputter deposition, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma enhanced atomic layer deposition (PEALD), and plasma enhanced chemical vapor deposition (PECVD). In other embodiments, the substrate is placed in a metalorganic vapor-phase epitaxy (MOVPE) reactor for epitaxy of LED device layers to grow the semiconductor layers <NUM>.

"Sputter deposition" as used herein refers to a physical vapor deposition (PVD) method of thin film deposition by sputtering. In sputter deposition, a material, e.g. a III-nitride, is ejected from a target that is a source onto a substrate. The technique is based on ion bombardment of a source material, the target. Ion bombardment results in a vapor due to a purely physical process, i.e., the sputtering of the target material.

As used according to some embodiments herein, "atomic layer deposition" (ALD) or "cyclical deposition" refers to a vapor phase technique used to deposit thin films on a substrate surface. The process of ALD involves the surface of a substrate, or a portion of substrate, being exposed to alternating precursors, i.e. two or more reactive compounds, to deposit a layer of material on the substrate surface. When the substrate is exposed to the alternating precursors, the precursors are introduced sequentially or simultaneously. The precursors are introduced into a reaction zone of a processing chamber, and the substrate, or portion of the substrate, is exposed separately to the precursors.

As used herein according to some embodiments, "chemical vapor deposition" refers to a process in which films of materials are deposited from the vapor phase by decomposition of chemicals on a substrate surface. In CVD, a substrate surface is exposed to precursors and/or co-reagents simultaneous or substantially simultaneously. As used herein, "substantially simultaneously" refers to either co-flow or where there is overlap for a majority of exposures of the precursors.

As used herein according to some embodiments, "plasma enhanced atomic layer deposition (PEALD)" refers to a technique for depositing thin films on a substrate. In some examples of PEALD processes relative to thermal ALD processes, a material may be formed from the same chemical precursors, but at a higher deposition rate and a lower temperature. A PEALD process, in general, a reactant gas and a reactant plasma are sequentially introduced into a process chamber having a substrate in the chamber. The first reactant gas is pulsed in the process chamber and is adsorbed onto the substrate surface. Thereafter, the reactant plasma is pulsed into the process chamber and reacts with the first reactant gas to form a deposition material, e.g. a thin film on a substrate. Similarly to a thermal ALD process, a purge step maybe conducted between the delivery of each of the reactants.

As used herein according to one or more embodiments, "plasma enhanced chemical vapor deposition (PECVD)" refers to a technique for depositing thin films on a substrate. In a PECVD process, a source material, which is in gas or liquid phase, such as a gas-phase III-nitride material or a vapor of a liquid-phase III-nitride material that have been entrained in a carrier gas, is introduced into a PECVD chamber. A plasma-initiated gas is also introduced into the chamber. The creation of plasma in the chamber creates excited radicals. The excited radicals are chemically bound to the surface of a substrate positioned in the chamber, forming the desired film thereon.

In one or more embodiments, the semiconductor layers <NUM> comprise a stack of undoped III-nitride material and doped III-nitride material. The III-nitride materials may be doped with one or more of silicon (Si), oxygen (O), boron (B), phosphorus (P), germanium (Ge), manganese (Mn), or magnesium (Mg) depending upon whether p-type or n-type III-nitride material is needed. In specific embodiments, the semiconductor layers <NUM> comprise an n-type layer <NUM>, an active layer <NUM> and a p-type layer <NUM>.

In one or more embodiments, the semiconductor layers <NUM> have a combined thickness in a range of from about <NUM> to about <NUM>, including a range of from about <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, including a range of from about <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, <NUM> to about <NUM>, or <NUM> to about <NUM>.

In one or more embodiments, an active region <NUM> is formed between the n-type layer <NUM> and the p-type layer <NUM>. The active region <NUM> may comprise any appropriate materials known to one of skill in the art. In one or more embodiments, the active region <NUM> is comprised of a III-nitride material multiple quantum wells (MQW), and a III-nitride electron blocking layer.

In one or more embodiments, the quantum well design in the epitaxy is changed to intentionally increase the peak shift with current. In some embodiments, the physical width of the quantum well is made wider. Accordingly, in one or more embodiments, the width of the quantum wells is in a range of from about <NUM> to about <NUM>.

In some embodiments, the semiconductor layers <NUM> and the substrate <NUM> are etched to form a mesa <NUM>. In the embodiment illustrated in <FIG>, the mesa <NUM> has a top surface 130t and at least one side wall <NUM>.

In one or more embodiments, the light emitting diode (LED) device <NUM> includes an anode contact <NUM> and a cathode contact <NUM>. In one or more embodiments, the anode contact <NUM> is divided into two regions, a first anode region <NUM> and a second anode region <NUM>. The first anode region <NUM> and the second anode region <NUM> are of unequal size. Typically, the first anode region and the second anode region are separated from one another by a gap <NUM>. Accordingly, in one or more embodiments, the anode contact <NUM> has a first anode region <NUM> and a second anode region <NUM> separated by a gap <NUM>. The first anode region <NUM> is on a top surface 130t of the mesa <NUM>. The second anode region <NUM> is adjacent to the first anode region <NUM>.

In one or more embodiments of the present invention, the first anode region <NUM> and the second anode region <NUM> are shorted together using a switch <NUM>. In one or more embodiments, the switch <NUM> is an electronic switch. The switch <NUM> connects the first anode region and the second anode region <NUM>.

The area ratio of the first anode region <NUM> to the sum of the area of both the first anode region <NUM> and the second anode region <NUM> is chosen such that, for a given input current, light emission having a centroid wavelength less than <NUM> is obtained when current is injected only to the first anode region <NUM>. In one or more embodiments, light emission having a centroid wavelength greater than <NUM> is obtained when current is injected to both the first anode region <NUM> and the second anode region <NUM>. In other words, the current density is changed by switching the anode area rather than by changing the current. Without intending to be bound by theory, it is thought that this approach allows current density (and color) to be changed without large changes in luminance.

In one or more embodiments, the gap <NUM> between the first anode region <NUM> and the second anode region <NUM> is filled with a dielectric layer <NUM> so that current flows through only the first anode region <NUM> when the switch <NUM> is open. In one or more embodiments, the gap <NUM> is has a width that is greater than <NUM> microns so that lateral current spreading from the first anode region <NUM> and the second anode region <NUM> through the p-type layer <NUM> with the switch <NUM> open is negligible. Optionally, for an LED that emits light from the side of the growth substrate <NUM>, a separate mirror layer <NUM> can be disposed on top of the anode contact <NUM> to prevent light from escaping through the gap <NUM> between the first anode region <NUM> and the second anode region <NUM>. An additional dielectric layer <NUM> may prevent shorting of the mirror <NUM> to the anode contact <NUM>.

In one or more embodiments, the anode contact <NUM> comprises a reflective material or a transparent conductor. In one or more embodiments, the anode contact <NUM> comprises one or more one or more of silver (Ag), indium tin oxide (ITO), nickel (Ni), palladium (Pd), platinum (Pt), and zinc oxide (ZnO). In one or more embodiments, the first anode region and the second anode region independently comprise a material selected from one or more of silver (Ag), indium tin oxide (ITO), nickel (Ni), palladium (Pd), platinum (Pt), and zinc oxide (ZnO).

As used herein, the term "dielectric" refers to an electrical insulator material that can be polarized by an applied electric field. In one or more embodiments, the dielectric layer <NUM> includes, but is not limited to, oxides, e.g., silicon oxide (SiO<NUM>), aluminum oxide (Al<NUM>O<NUM>), nitrides, e.g., silicon nitride (Si<NUM>N<NUM>). In one or more embodiments, the dielectric layer <NUM> comprises silicon nitride (Si<NUM>N<NUM>). In one or more embodiments, the dielectric layer <NUM> comprises silicon oxide (SiO<NUM>). In some embodiments, the dielectric layer <NUM> composition is non-stoichiometric relative to the ideal molecular formula. For example, in some embodiments, the dielectric layer includes, but is not limited to, oxides (e.g., silicon oxide, aluminum oxide), nitrides (e.g., silicon nitride (SiN)), oxycarbides (e.g. silicon oxycarbide (SiOC)), and oxynitrocarbides (e.g. silicon oxycarbonitride (SiNCO)). In one or more embodiments, the dielectric layer <NUM> comprises one or more of silicon oxide (SiO<NUM>), aluminum oxide (Al<NUM>O<NUM>), silicon nitride (SiNx), titanium oxide (TiO<NUM>), niobium oxide (Nb<NUM>O<NUM>), zirconium oxide (ZrO<NUM>), and hafnium oxide (HfO<NUM>).

In one or more embodiments, the dielectric layer <NUM> is deposited by one or more of sputter deposition, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma enhanced atomic layer deposition (PEALD), and plasma enhanced chemical vapor deposition (PECVD).

In one or more embodiments, the cathode contact <NUM> is adjacent to the anode contact <NUM> and in electrical communication with the n-type layer <NUM>.

In one or more embodiments, the cathode contact <NUM> comprises a metal selected from the group consisting of titanium (Ti), aluminum (Al), chromium (Cr), silver (Ag), gold (Ag), and alloys or multilayers thereof.

With reference to <FIG>, an electrical terminal 116t for operation of the switch <NUM> is required, in addition to the usual cathode contact terminal 108t and anode contact <NUM> terminal 113t of an LED. <FIG> illustrates a process flow diagram of a method <NUM> according to one or more embodiments of the present invention. In one or more embodiments, the method <NUM> of operating the LED of <FIG> requires, at operation <NUM>, an LED is provided for processing. As used in this specification and the appended claims, the term "provided" means that the LED is made available for operation. In some embodiments, the LED has already been fabricated. In other embodiments, the LED is fabricated according to one or more embodiments described herein. At operation <NUM>, the switch <NUM> is opened and, at operation <NUM>, a current is flowed through the anode contact <NUM> to the first anode contact region <NUM> to emit light having a centroid wavelength less than <NUM>.

<FIG> illustrates a process flow diagram of a method <NUM> according to one or more embodiments of the present invention. In one or more embodiments, the method <NUM> of operating the LED of <FIG> requires, at operation <NUM>, an LED is provided for processing. At operation <NUM>, closing the switch <NUM> is closed and, at operation <NUM>, a current is flowed through the anode contact <NUM> to the first anode contact region <NUM> to emit light having a centroid wavelength greater than <NUM>.

<FIG> illustrates a cross-sectional view of an LED device according to one or more embodiments not forming part of the present invention. <FIG> illustrates a top view of the LED device of <FIG>. Referring to <FIG>, in one or more embodiments semiconductor layers <NUM> are grown on a substrate <NUM>. The semiconductor layers <NUM> according to one or more embodiments comprise epitaxial layers, III-nitride layers or epitaxial III-nitride layers. In one or more embodiments, the semiconductor layers are epitaxial semiconductor layers having a thickness at least <NUM> micron.

The substrate <NUM> may be any substrate known to one of skill in the art. In one or more embodiments, the substrate <NUM> comprises one or more of sapphire, silicon carbide, silicon (Si), quartz, magnesium oxide (MgO), zinc oxide (ZnO), spinel, and the like. In one or more embodiments, the substrate <NUM> is not patterned prior to the growth of the Epi-layer. Thus, in some embodiments, the substrate <NUM> is not patterned and can be considered to be flat or substantially flat. In other embodiments, the substrate <NUM> is patterned, e.g. patterned sapphire substrate (PSS).

In one or more embodiments, the semiconductor layers <NUM> comprise a stack of undoped III-nitride material and doped III-nitride material. The III-nitride materials may be doped with one or more of silicon (Si), oxygen (O), germanium (Ge), tin (Sn), zinc (Zn), beryllium (Be), carbon (C), or magnesium (Mg) depending upon whether p-type or n-type III-nitride material is needed. In specific embodiments, the semiconductor layers <NUM> comprise an n-type layer <NUM>, an active layer <NUM> and a p-type layer <NUM>.

In some embodiments, the semiconductor layers <NUM> and the substrate <NUM> are etched to form arrays of mesas 230a, 230b. In the embodiment illustrated in <FIG>, the mesas 230a, 23b have a top surface 230t and at least one side wall <NUM>. The mesa array includes a first mesa 230a and a second mesa 230b separated by a trench <NUM>. The first mesa 230a and the second mesa 230b include semiconductor layers <NUM>. In one or more embodiments, the trench <NUM> has at least one side wall <NUM>. The trench <NUM> extends to the n-type layer <NUM>. In one or more embodiments, the first mesa 230a has a first width, w<NUM>, and the second mesa 230b has a second width, w<NUM>. In one or more embodiments, the first width, w<NUM>, is greater than the second width, w<NUM>.

In one or more embodiments, the light emitting diode (LED) device <NUM> includes an anode contact <NUM> and a cathode contact <NUM>. In one or more embodiments, the anode contact <NUM> is divided into two regions, a first anode region <NUM> and a second anode region <NUM>. The first anode region <NUM> and the second anode region <NUM> are of unequal size. The first anode region <NUM> is on a top surface 230t of the first mesa 230a. The second anode region <NUM> is on a top surface 230t of the second mesa 230b.

In one or more embodiments, the size of the mesa 230b is smaller in the array that emits light having a centroid wavelength less than <NUM> than it is in the array that emits light having a centroid wavelength greater than <NUM>. In one or more embodiments, each array has its own anode region <NUM>, <NUM>, which may be connected to its own separate current driver, or to one current driver that is switched between the two anodes using circuitry external to the LED. Thus, for the same driving current, the array with smaller mesas 230b emits light having a centroid wavelength less than <NUM>, while the array with larger mesas 230a emits light having a centroid wavelength greater than <NUM> of similar luminance level. In one or more embodiments, the required ratio of small to large areas of the mesas can be found by spectrum vs. current density measurements of an LED with standard anode contact built from the same type of epitaxial wafer.

In one or more embodiments a dielectric layer <NUM> is on the at least one side wall <NUM> of the trench <NUM>. In one or more embodiments, the dielectric layer <NUM> includes, but is not limited to, oxides, e.g., silicon oxide (SiO<NUM>), aluminum oxide (Al<NUM>O<NUM>), nitrides, e.g., silicon nitride (Si<NUM>N<NUM>). In one or more embodiments, the dielectric layer <NUM> comprises silicon nitride (Si<NUM>N<NUM>). In one or more embodiments, the dielectric layer <NUM> comprises silicon oxide (SiO<NUM>). In some embodiments, the dielectric layer <NUM> composition is non-stoichiometric relative to the ideal molecular formula. For example, in some embodiments, the dielectric layer includes, but is not limited to, oxides (e.g., silicon oxide, aluminum oxide), nitrides (e.g., silicon nitride (SiN)), oxycarbides (e.g. silicon oxycarbide (SiOC)), and oxynitrocarbides (e.g. silicon oxycarbonitride (SiNCO)). In one or more embodiments, the dielectric layer <NUM> comprises one or more of silicon oxide (SiO<NUM>), aluminum oxide (Al<NUM>O<NUM>), silicon nitride (SiNx), titanium oxide (TiO<NUM>), niobium oxide (Nb<NUM>O<NUM>), zirconium oxide (ZrO<NUM>), and hafnium oxide (HfO<NUM>).

In one or more embodiments, the anode contact <NUM> comprises a reflective material or a transparent conductor. In one or more embodiments, the anode contact <NUM> comprises one or more one or more of silver (Ag), indium tin oxide (ITO), nickel (Ni), palladium (Pd), platinum (Pt), and zinc oxide (ZnO). In one or more embodiments, the first anode region <NUM> and the second anode region <NUM> independently comprise a material selected from one or more of silver (Ag), indium tin oxide (ITO), nickel (Ni), palladium (Pd), platinum (Pt), and zinc oxide (ZnO).

In one or more embodiments, the cathode contact <NUM> comprises a metal selected from the group consisting of comprises a metal selected from the group consisting of titanium (Ti), aluminum (Al), chromium (Cr), silver (Ag), gold (Ag), and alloys or multilayers thereof.

With reference to <FIG>, an electrical terminal <NUM> for the array that emits light having a centroid wavelength less than <NUM> and an electrical terminal <NUM> for the array that emits light having a centroid wavelength greater than <NUM> are necessary. In addition, a cathode contact terminal <NUM> is present.

<FIG> illustrates a process flow diagram of a method <NUM> according to one or more embodiments not forming part of the present invention. In one or more embodiments, the method <NUM> of operating the LED of <FIG>, at operation <NUM>, an LED is provided for processing. As used in this specification and the appended claims, the term "provided" means that the LED is made available for operation. In some embodiments, the LED has already been fabricated. In other embodiments, the LED is fabricated according to one or more embodiments described herein. At operation <NUM>, a current is flowed through the anode contact <NUM> to the first anode contact region <NUM> to emit light having a centroid wavelength less than <NUM>.

<FIG> illustrates a process flow diagram of a method <NUM> according to one or more embodiments not forming part of the present invention. In one or more embodiments, the method <NUM> of operating the LED of <FIG> requires, at operation <NUM>, an LED is provided for processing. At operation <NUM>, a current is flowed through the anode contact <NUM> to the first anode contact region <NUM> and to the second anode contact region <NUM> to emit light having a centroid wavelength greater than <NUM>.

<FIG> illustrates a top view of an LED device according to one or more embodiments not forming part of the present invention. <FIG> illustrates a cross-sectional view taken along lines B<NUM>-B'<NUM> and B<NUM>-B'<NUM> of the LED device of <FIG>. <FIG> illustrates a cross-sectional view taken along lines C<NUM>-C'<NUM> and C<NUM>-C'<NUM> of the LED device of <FIG>. Referring to <FIG>, in one or more embodiments semiconductor layers <NUM> are grown on a substrate <NUM>. The semiconductor layers <NUM> according to one or more embodiments comprise epitaxial layers, III-nitride layers or epitaxial III-nitride layers. In one or more embodiments, the semiconductor layers are epitaxial semiconductor layers having a thickness at least <NUM> micron.

In some embodiments, the semiconductor layers <NUM> and the substrate <NUM> are etched to form arrays <NUM>, <NUM> of mesas <NUM>, <NUM>. In one or more embodiments, the number of mesas <NUM>, <NUM> in each array <NUM>, <NUM> is varied. In one or more embodiments, the array <NUM> that emits light having a centroid wavelength greater than <NUM> has more mesas <NUM> than the array <NUM> that emits light having a centroid wavelength less than <NUM>, which has fewer mesas <NUM>. The required ratio of numbers of mesas <NUM>, <NUM> in each array <NUM>, <NUM> can be found by spectrum versus current density measurements of an LED with standard anode contact built from the same type of epitaxial wafer.

In the embodiment not forming part of the present invention illustrated in <FIG> the mesas <NUM> have a top surface 336t and at least one side wall <NUM>. The mesa array <NUM> includes a plurality of mesas <NUM> separated by a trench <NUM>. The plurality of mesas <NUM> include semiconductor layers <NUM>. In one or more embodiments, the trench <NUM> has at least one side wall <NUM>. The trench <NUM> extends to the n-type layer <NUM>.

In the embodiment not forming part of the present invention illustrated in <FIG> the mesas <NUM> have a top surface 322t and at least one side wall <NUM>. The mesa array <NUM> includes a plurality of mesas <NUM> separated by a trench <NUM>. The plurality of mesas <NUM> include semiconductor layers <NUM>. In one or more embodiments, the trench <NUM> has at least one side wall <NUM>. The trench <NUM> extends to the n-type layer <NUM>.

In one or more embodiments, the light emitting diode (LED) device <NUM> includes an anode contact is divided into two regions, a first anode region <NUM> and a second anode region <NUM>. The first anode region <NUM> is on a top surface 336t of the plurality of mesas <NUM>. The second anode region <NUM> is on a top surface 322t of the plurality of mesas <NUM>.

Referring to <FIG>, in one or more embodiments a dielectric layer <NUM> fills the trench <NUM>. Referring to <FIG>, in one or more embodiments a dielectric layer <NUM> fills the trench <NUM>. In one or more embodiments, the dielectric layer <NUM> includes, but is not limited to, oxides, e.g., silicon oxide (SiO<NUM>), aluminum oxide (Al<NUM>O<NUM>), nitrides, e.g., silicon nitride (Si<NUM>N<NUM>). In one or more embodiments, the dielectric layer <NUM> comprises silicon nitride (Si<NUM>N<NUM>). In one or more embodiments, the dielectric layer <NUM> comprises silicon oxide (SiO<NUM>). In some embodiments, the dielectric layer <NUM> composition is non-stoichiometric relative to the ideal molecular formula. For example, in some embodiments, the dielectric layer includes, but is not limited to, oxides (e.g., silicon oxide, aluminum oxide), nitrides (e.g., silicon nitride (SiN)), oxycarbides (e.g. silicon oxycarbide (SiOC)), and oxynitrocarbides (e.g. silicon oxycarbonitride (SiNCO)). In one or more embodiments, the dielectric layer <NUM> comprises one or more of silicon oxide (SiO<NUM>), aluminum oxide (Al<NUM>O<NUM>), silicon nitride (SiNx), titanium oxide (TiO<NUM>), niobium oxide (Nb<NUM>O<NUM>), zirconium oxide (ZrO<NUM>), and hafnium oxide (HfO<NUM>).

In one or more embodiments, the anode contact comprises a reflective material or a transparent conductor. In one or more embodiments, the anode contact comprises one or more one or more of silver (Ag), indium tin oxide (ITO), nickel (Ni), palladium (Pd), platinum (Pt), and zinc oxide (ZnO). In one or more embodiments, the first anode region <NUM> and the second anode region <NUM> independently comprise a material selected from one or more of silver (Ag), indium tin oxide (ITO), nickel (Ni), palladium (Pd), platinum (Pt), and zinc oxide (ZnO).

Referring to <FIG>, in one or more embodiments, the light emitting diode (LED) device <NUM> includes a cathode contact <NUM>. In one or more embodiments, the cathode contact <NUM> is adjacent to the mesa array <NUM> and the mesa array <NUM> and in electrical communication with the n-type layer <NUM>.

<FIG> illustrates a process flow diagram of a method <NUM> according to one or more embodiments not forming part of the present invention. In one or more embodiments, the method <NUM> of operating the LED of <FIG>, at operation <NUM>, an LED is provided for processing. As used in this specification and the appended claims, the term "provided" means that the LED is made available for operation. In some embodiments, the LED has already been fabricated. In other embodiments, the LED is fabricated according to one or more embodiments described herein. At operation <NUM>, through the anode contact <NUM> to emit light having a centroid wavelength less than <NUM>.

<FIG> illustrates a process flow diagram of a method <NUM> according to one or more embodiments not forming part of the present invention. In one or more embodiments, the method <NUM> of operating the LED of <FIG> requires, at operation <NUM>, an LED is provided for processing. At operation <NUM>, a current is flowed through the anode contact <NUM> to emit light having a centroid wavelength greater than <NUM>.

The use of the terms "a" and "an" and "the" and similar referents in the context of describing the materials and methods discussed herein (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the materials and methods and does not pose a limitation on the scope unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosed materials and methods.

Reference throughout this specification to the terms first, second, third, etc. may be used herein to describe various elements, and these elements should not be limited by these terms. These terms may be used to distinguish one element from another.

Reference throughout this specification to a layer, region, or substrate as being "on" or extending "onto" another element, means that it may be directly on or extend directly onto the other element or intervening elements may also be present. When an element is referred to as being "directly on" or extending "directly onto" another element, there may be no intervening elements present. Furthermore, when an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element and/or connected or coupled to the other element via one or more intervening elements. When an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present between the element and the other element. It will be understood that these terms are intended to encompass different orientations of the element in addition to any orientation depicted in the figures.

Relative terms such as "below," "above," "upper,", "lower," "horizontal" or "vertical" may be used herein to describe a relationship of one element, layer, or region to another element, layer, or region as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

Reference throughout this specification to "one embodiment," "certain embodiments," "one or more embodiments" or "an embodiment" means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of the phrases such as "in one or more embodiments," "in certain embodiments," "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment of the disclosure.

Although the disclosure herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present disclosure.

Claim 1:
A light emitting diode (LED) device comprising:
a mesa (<NUM>) comprising semiconductor layers, the semiconductor layers including an n-type layer (<NUM>), an active layer (<NUM>), and a p-type layer (<NUM>);
characterized by
an anode contact (<NUM>) comprising a first anode region (<NUM>) and a second anode region (<NUM>) separated by a gap (<NUM>), the first anode region (<NUM>) on a top surface (130t) of the mesa (<NUM>), the second anode region (<NUM>) adjacent the first anode region (<NUM>);
a switch (<NUM>) connecting the first anode region (<NUM>) and the second anode region (<NUM>); and
a cathode contact (<NUM>) adjacent the anode contact (<NUM>) and in electrical communication with the n-type layer (<NUM>).