KR-102963536-B1 - High-resolution monolithic RGB array

KR102963536B1KR 102963536 B1KR102963536 B1KR 102963536B1KR-102963536-B1

Abstract

A light-emitting diode structure comprising: a p-type region; an n-type region; a light-emitting region for recombination of carriers that can be injected by the p-type region and the n-type region; and a via penetrating the light-emitting region, wherein the via defines the outer periphery of the light-emitting surface of at least one pixel and comprises a material configured to enable carrier injection into the p-type region or the n-type region, wherein one of the p-type region and the n-type region is configured such that carriers generated in one of the p-type region and the n-type region diffuse through the other of the n-type region and the p-type region before recombination within the light-emitting region.

Inventors

피노스, 안드레아
김, 준-연
메주아리, 사미르
탄, 웨이신

Assignees

플레세이 세미컨덕터스 리미티드

Dates

Publication Date: 20260513
Application Date: 20210315
Priority Date: 20200318

Claims (20)

p-type region; n-type region; A light-emitting region for the recombination of carriers that can be injected by the above p-type region and the above n-type region; and It includes a via penetrating the above-mentioned light-emitting region, A light-emitting diode structure comprising a material configured to define the outer periphery of the light-emitting surface of at least one pixel and to enable carrier injection into the p-type region or the n-type region, wherein one of the p-type region and the n-type region is configured such that carriers generated in one of the p-type region and the n-type region diffuse through the other of the n-type region and the p-type region before recombination within the light-emitting region.
A light-emitting diode structure according to claim 1, wherein the light-emitting region comprises at least one epitaxial quantum well layer, or the p-type region and the n-type region are on the same side of the light-emitting region.
A light-emitting diode structure according to claim 1 or 2, wherein the material comprises at least a portion of the n-type region or the p-type region, or the material comprises a conductive material, and the conductive material is a metal.
A light-emitting diode structure according to claim 1, comprising an additional light-emitting region, wherein the light-emitting region and the additional light-emitting region are separated by an undoped region to provide a stack of light-emitting regions, the via penetrates both the light-emitting region and the additional light-emitting region, the light-emitting region and the additional light-emitting region are configured to emit light of different wavelengths, and the light-emitting region and the additional light-emitting region are arranged such that the surface areas of the light-emitting region and the additional light-emitting region partially overlap.
A light-emitting diode structure according to claim 4, comprising at least three light-emitting regions, wherein one of the light-emitting regions emits blue light, one of the light-emitting regions emits green light, and one of the light-emitting regions emits red light.
A light-emitting diode structure according to claim 1, wherein the via is a grid via defining an array including a plurality of pixels, the grid via is arranged to provide a common electrode, at least one of the plurality of pixels includes an additional electrode, the additional electrode is located at the center within the outer periphery of the light-emitting surface of at least one pixel, and at least two pixels are configured to emit light of different wavelengths.
A light-emitting diode structure according to claim 1, wherein at least one of the light-emitting region and the additional light-emitting region is formed on an undoped epitaxial layer, or at least one of the light-emitting region and the additional light-emitting region is formed between undoped epitaxial layers, and the undoped epitaxial layer is formed on a barrier layer configured to block vertical carrier diffusion, wherein the undoped epitaxial layer is gallium nitride and the barrier layer is AlGaN.
A light-emitting diode structure according to claim 1, wherein at least one of the n-type region and the p-type region is formed within a via connected to a planar n-type region or a planar p-type region, respectively.
A light-emitting diode structure according to claim 1, wherein at least one of the n-type region and the p-type region is formed by selective region growth.
A light-emitting diode structure according to claim 1, wherein the via is an etched via, and the light-emitting surface has an area based on the diffusion length of a carrier within the light-emitting region, and the area of the light-emitting surface is 100 μm² or less.
A light-emitting diode structure according to claim 1, wherein at least one pixel is entirely defined by a single electrode.
A high-resolution micro LED array comprising the light-emitting diode structure of claim 1.
In claim 12, the array is a multicolor array, and the array is a high-resolution micro LED array having a pixel pitch of less than 10 μm.
As a method of forming a light-emitting diode structure, Step of forming a p-type region; Step of forming an n-type region; A step of forming a light-emitting region for the recombination of carriers that can be injected by the above p-type region and the above n-type region; and The step of forming a via penetrating the light-emitting region, wherein A method comprising a material configured to define the outer periphery of the light-emitting surface of at least one pixel and to enable carrier injection into the p-type region or the n-type region, wherein one of the p-type region and the n-type region is configured such that a carrier generated in one of the p-type region and the n-type region diffuses through the other of the n-type region and the p-type region before recombination within the light-emitting region.
In claim 14, the step of forming the light-emitting region comprises the step of forming at least one epitaxial quantum well layer.
A method according to claim 14, comprising the step of forming the p-type region and the n-type region on the same side of the light-emitting region.
A method according to any one of claims 14 to 16, wherein the material comprises at least a portion of the p-type region or the n-type region, or the material comprises a conductive material, and the conductive material is a metal.
A method according to claim 14, comprising the step of providing an additional light-emitting region, wherein the light-emitting region and the additional light-emitting region are separated by an undoped region to provide a stack of light-emitting regions, the via penetrates both the light-emitting region and the additional light-emitting region, the light-emitting region and the additional light-emitting region are configured to emit light of different wavelengths, and the light-emitting region and the additional light-emitting region are arranged such that the surface areas of the light-emitting region and the additional light-emitting region partially overlap.
A method according to claim 18, comprising at least three light-emitting regions, wherein one of the light-emitting regions emits blue light, one of the light-emitting regions emits green light, one of the light-emitting regions emits red light, and the planar surface area of the additional light-emitting region is smaller than the planar surface area of the light-emitting region.
A method according to claim 14, wherein the via is a grid via defining a plurality of pixels, the grid is arranged to provide a common electrode, and further comprises the step of forming an additional electrode for at least one of the pixels, wherein the additional electrode is formed in the center within the outer periphery of the light-emitting surface of the at least one pixel, and at least two pixels are configured to emit light of different wavelengths.

Description

High-resolution monolithic RGB array The present invention relates to a light-emitting diode structure and a method for forming a light-emitting diode structure. Specifically, but non-exclusively, the present invention relates to a high-resolution monolithic light-emitting diode structure array. Conventional red-green-blue (RGB) micro-light-emitting diode (μLED) arrays of light-emitting pixels are typically achieved using pick-and-place techniques or by using color-changing materials integrated into or deposited on standard planar light-emitting diode (LED) structures. However, as the pixel pitch within such arrays is reduced to a very small pitch (e.g., less than 5 μm) to provide higher resolution arrays, many difficulties arise. For example, the use of take-and-place can be impractical due to high costs, low throughput, and limitations in positional accuracy during the transfer of micro-LEDs. In the case of color conversion, the use of such techniques is limited by the size of the phosphor used for color conversion, which typically exceeds 10 μm (i.e., larger than the pixel pitch in an array with a very small pitch required for higher resolution). Furthermore, color conversion techniques are prone to low reliability and inefficiency due to the small absorption coefficients associated with quantum dots (QDs). For instance, a thickness of color conversion QD material exceeding 10 μm is required to completely absorb the blue emission that excites it, making it unsuitable for arrays with very small pixel pitches. To prevent the transfer of LEDs and provide high-quality, efficient emission, it is beneficial to provide a native LED array on the same substrate. One approach to constructing a native LED array on the same substrate relies on the selective region growth of nanowires, which is an array of individual structures grown substantially perpendicularly to a patterned growth substrate to form light-emitting structures, where the light-emitting surface is defined by the cross-sectional area of the nanowire using conventional epitaxial quantum well structures grown between epitaxial n-type and p-type doping layers. However, the growth of such nanowires is generally difficult to control and may suffer from severe limitations in achievable light efficiency and color gamut due to, for example, poor light extraction efficiency and impurity incorporation. The detailed description of embodiments of the present invention is described with reference to the drawings merely for illustrative purposes. Figure 1a shows a cross-sectional view of an epitaxial structure. FIG. 1b shows a cross-sectional view of a fabricated epitaxial structure. FIG. 1c shows a cross-sectional view of a fabricated epitaxial structure. FIG. 1d shows a cross-sectional view of a fabricated epitaxial structure. FIG. 1e shows a cross-sectional view of a fabricated epitaxial structure. FIG. 1f shows a cross-sectional view of a fabricated epitaxial structure. FIG. 1g shows a cross-sectional view of a processed epitaxial structure. Figure 2 shows a plan view of the fabricated epitaxial structure of Figure 1c. Figure 3 shows a plan view of the fabricated epitaxial structure of Figure 1f. Figure 4 shows a cross-sectional view of a fabricated epitaxial structure. Figure 5 shows a cross-sectional view of a fabricated epitaxial structure. Figure 6 shows a cross-sectional view of a fabricated epitaxial structure. FIG. 7 illustrates a cross-sectional view of an epitaxial structure having three different light-emitting regions. FIG. 8a shows a cross-sectional view of the fabricated epitaxial structure of FIG. 7. Figure 8b shows a plan view of the fabricated epitaxial structure of Figure 8a. Figure 9a shows a cross-sectional view of another fabricated epitaxial structure of Figure 8a. Fig. 9b shows a plan view of another fabricated epitaxial structure of Fig. 8a. FIG. 10a illustrates a light-emitting structure having three different light-emitting regions. Figure 10b shows a plan view of the light-emitting structure of Figure 10a. Figure 11 illustrates the processed light-emitting structure of Figure 10a. Light-emitting diodes (LEDs) are typically formed by processing light-emitting structures grown by forming epitaxial crystalline layers on a relatively large wafer substrate within a reactor, such as, for example, an organometallic chemical vapor deposition (MOCVD) reactor, a molecular beam epitaxy (MBE) reactor, or other chemical vapor deposition reactors. For the reasons mentioned above, known methods for producing high-resolution micro-LED arrays face difficulties in processing LEDs produced by crystalline structures grown on a relatively large wafer substrate to provide micro-LEDs for high-resolution arrays. The use of nanowire LED arrays to overcome these processing problems results in difficulties in controlling the growth process, as well as generally poorer performance than that exhibited in conventional growth of LEDs on relatively large wafer substr