Micro LEDs, micro LED panels and micro LED chips

Abstract

A micro LED (300) includes: a first type semiconductor layer (310); a light-emitting layer (320) formed on the first type semiconductor layer (310); and a second type semiconductor layer (330) formed on the light-emitting layer (320); wherein the bottom sidewall of the second type semiconductor layer (330) is aligned with the sidewall of the first type semiconductor layer (310); and the sidewall of the second type semiconductor layer (330) does not conform to a straight line.

Description

Technical Field

[0001] This disclosure generally relates to light-emitting diodes, and more specifically to a miniature light-emitting diode (LED), a miniature LED panel, and a miniature LED chip. Background Technology

[0002] Miniature pixel light-emitting diodes (also known as micro-LEDs, micro-LEDs, or μ-LEDs) are becoming increasingly important due to their use in a variety of applications, including self-emitting microdisplays, visible light communication, and optogenetics. For display applications, arrays of micro-LEDs with pixel sizes as small as 12 μm have been demonstrated. Micro-LEDs exhibit higher output performance than conventional LEDs due to better strain relaxation, improved light extraction efficiency, and uniform current spreading. Compared to conventional LEDs, micro-LEDs also exhibit improved thermal effects and can operate at higher current densities.

[0003] However, smaller LED pixels with higher current densities experience redshift, lower maximum efficiency, and non-uniform emission at high current densities, attributed to manufacturing process damage that leads to degraded current injection. Furthermore, peak external quantum efficiency (EQE) and internal quantum efficiency (IQE) decrease significantly with decreasing chip size. The reduced EQE is explained by nonradiative recombination caused by etching damage, while the reduced IQE is attributed to poor current injection and electron leakage current in microLEDs.

[0004] The above discussion provides technical solutions to aid in understanding this disclosure and does not constitute an admission that the above are prior art. Summary of the Invention

[0005] Embodiments of this disclosure provide a micro LED. The micro LED includes: a first type semiconductor layer; a light-emitting layer formed on the first type semiconductor layer; and a second type semiconductor layer formed on the light-emitting layer; wherein the bottom sidewall of the second type semiconductor layer is aligned with the sidewall of the first type semiconductor layer; and the sidewall of the second type semiconductor layer does not conform to a straight line.

[0006] Embodiments of this disclosure also provide a micro LED panel. The micro LED panel includes two or more of the aforementioned micro LEDs, wherein the light-emitting layer is continuous between adjacent micro LEDs.

[0007] Embodiments of this disclosure also provide a micro LED chip. The micro LED chip includes one or more of the aforementioned micro LED panels.

[0008] Other advantages and features of this disclosure will be further understood through the following detailed description and accompanying drawings. Attached Figure Description

[0009] Embodiments and aspects of this disclosure are illustrated in the following detailed description and accompanying drawings. The various features shown in the drawings are not drawn to scale.

[0010] Figure 1 This is a structural diagram of a first exemplary microLED according to some embodiments of this disclosure.

[0011] Figure 2 This is a structural diagram of a second exemplary microLED according to some embodiments of this disclosure.

[0012] Figure 3 This is a structural diagram of a third exemplary microLED according to some embodiments of this disclosure.

[0013] Figure 4 This is a structural diagram of an exemplary micro-LED panel according to some embodiments of this disclosure.

[0014] Figure 5 This is a structural diagram showing adjacent micro-LEDs according to some embodiments of this disclosure.

[0015] Figure 6 This is a structural diagram illustrating another adjacent micro-LED according to some embodiments of this disclosure.

[0016] Figure 7 This is a structural diagram of an exemplary microLED chip according to some embodiments of this disclosure. Detailed Implementation

[0017] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings, wherein the same numerals in different drawings denote the same or similar elements unless otherwise indicated. The implementations set forth in the following description of the exemplary embodiments do not represent all implementations consistent with this disclosure. Rather, they are merely examples of devices and methods consistent with the aspects set forth in the appended claims and relevant to the invention. Specific aspects of this disclosure are described below in more detail. In the event of any conflict with terms and / or definitions incorporated by reference, the terms and definitions provided herein shall prevail.

[0018] To overcome the above-mentioned shortcomings, this disclosure provides a micro LED configured to minimize surface carrier loss and optimize the quantum well sidewall region.

[0019] More specifically, the micro-LED embodiments disclosed herein reduce the size of the second type of semiconductor layer to prevent carrier diffusion between adjacent LEDs and to form a continuous quantum well effect at the sidewalls of the quantum well, thereby minimizing nonradiative recombination of surface carriers. Furthermore, the isolation structure formed between adjacent LEDs suppresses photoelectric crosstalk. Additionally, the maximum width of the first electrode is smaller than the minimum width of the first type of semiconductor layer to reduce the carrier expansion region.

[0020] Figure 1 This is a structural diagram showing a side cross-sectional view of an exemplary micro-LED 100 according to some embodiments of this disclosure. Reference Figure 1 The micro-LED 100 includes a first type semiconductor layer 110, a light-emitting layer 120, and a second type semiconductor layer 130. The light-emitting layer 120 is formed on the first type semiconductor layer 110, and the second type semiconductor layer 130 is formed on the light-emitting layer 120. In some embodiments, the bottom width of the second type semiconductor layer 130 is smaller than the top width of the first type semiconductor layer 110. Therefore, at least a portion of the sidewalls of the second type semiconductor layer 130 is not aligned with the sidewalls of the first type semiconductor layer 110. In some embodiments, the maximum width of the second type semiconductor layer 130 is smaller than the minimum width of the first type semiconductor layer 110. In some embodiments, such as... Figure 1 As shown, the widths of the second type semiconductor layer 130 and the first type semiconductor layer 110 gradually increase from top to bottom. Therefore, the bottom width of the second type semiconductor layer 130 is smaller than the top width of the first type semiconductor layer 110. In this embodiment, the sidewalls of the first type semiconductor layer 110 are not aligned with the sidewalls of the second type semiconductor layer 130, but the sidewalls of the second type semiconductor layer 130 conform to a straight line. The sidewalls of the light-emitting layer 120 extend horizontally beyond the sidewalls of the second type semiconductor layer 130. In some embodiments, the sidewalls of the first type semiconductor layer 110 are aligned with the sidewalls of the light-emitting layer 120.

[0021] In some embodiments, the microLED 100 further includes a first electrode 140 and a second electrode 150. The first electrode 140 is formed at the bottom of the first type semiconductor layer 110, and the second electrode 150 is formed at the top of the second type semiconductor layer 130. The minimum width of the first electrode 140 is the same as the maximum width of the light-emitting layer 120, but greater than the maximum width of the second electrode 150. This structure ensures that the light-emitting area is maximized and improves luminous efficiency.

[0022] In some embodiments, the first type semiconductor layer 110, the second type semiconductor layer 130, the light-emitting layer 120, the first electrode 140, and the second electrode 150 can have different shapes, such as truncated cones, cylinders, or cubes. Therefore, in some embodiments, as seen in a side cross-sectional view of the microLED structure, each of the first type semiconductor layer, the second type semiconductor layer, the light-emitting layer, the first electrode, and the second electrode can each have the same width from top to bottom.

[0023] In some embodiments, the width of the first type semiconductor layer 110 and the width of the second type semiconductor layer 130 gradually decrease from top to bottom, and the sidewalls of the first type semiconductor layer 110 are not aligned with the sidewalls of the second type semiconductor layer 130.

[0024] Figure 2 This is a structural diagram showing a side cross-sectional view of an exemplary micro-LED 200 according to some embodiments of this disclosure. Reference Figure 2 The micro-LED 200 includes a second type semiconductor layer 230, wherein the sidewalls of the second type semiconductor layer 230 are misaligned. The sidewalls of the second type semiconductor layer 230 include one or more step structures 231 and 232. The sidewalls of the second type semiconductor layer 230 are not straight; that is, the sidewalls of step structures 231 and 232 are misaligned. The bottom width of the second type semiconductor layer 230 (e.g., the bottom width of step structure 231) is smaller than the top width of the first type semiconductor layer 210. The bottom width of step structure 232 is smaller than the top width of step structure 231. The maximum width of the second electrode 250 formed at the top of step structure 232 is smaller than the minimum width of the second type semiconductor layer 230 (e.g., the top width of step structure 232), and the maximum width of the first electrode 240 formed at the bottom of the first type semiconductor layer 210 is smaller than the minimum width of the first type semiconductor layer 210. In some embodiments, the thickness of the upper step structure 232 of the second type semiconductor layer 230 is greater than the thickness of the bottom step structure 231 of the second type semiconductor layer 230. In some embodiments, the maximum width of the first electrode 240 is less than or equal to the minimum width of the second electrode 250.

[0025] Figure 3 This is a structural diagram showing a side cross-sectional view of an exemplary micro-LED 300 according to some embodiments of this disclosure. Reference Figure 3The micro-LED 300 includes a second-type semiconductor layer 330. The second-type semiconductor layer 330 includes one or more stepped structures 331 and 332. The sidewalls of the second-type semiconductor layer 330 are not straight; that is, the sidewalls of stepped structures 331 and 332 are not aligned. The bottom sidewall of the second-type semiconductor layer 330 (e.g., the sidewall of stepped structure 331) is aligned with the sidewall of the first-type semiconductor layer 310. Figure 3 As shown, the sidewalls of the bottom step structure 331 are further aligned with the sidewalls of the light-emitting layer 320 between the first type semiconductor layer 310 and the second type semiconductor layer 330. The sidewalls of the bottom step structure 331 are further aligned with the sidewalls of the first type semiconductor layer 310. The bottom width of the bottom step structure 331 is the same as the top width of the light-emitting layer 320. The maximum width of the first electrode 340 formed at the bottom of the first type semiconductor layer 310 is less than or equal to the minimum width of the second electrode 350 formed at the top of the second type semiconductor layer 330.

[0026] When a microLED chip comprises one or more of the aforementioned microLEDs, a light-emitting layer and a first-type semiconductor layer are continuously formed over the entire microLED chip. For each microLED, the minimum width of the second-type semiconductor layer is smaller than the minimum width of the first-type semiconductor layer and smaller than the minimum width of the first electrode. Furthermore, isolation structures are formed between adjacent microLEDs to prevent crosstalk between them.

[0027] Figure 4 This is a structural diagram showing a plan view of an exemplary micro-LED panel 400 according to some embodiments of this disclosure. Figure 4 As shown, the microLED panel 400 includes two or more microLEDs 410. One or more microLEDs 410 are arranged in an array on the microLED panel 400. Figure 5 This is a side cross-sectional view showing the structure of exemplary adjacent micro-LEDs 500a and 500b included in micro-LED panel 400, according to some embodiments of this disclosure. The structures of micro-LEDs 500a and 500b can be... Figure 1 The micro-LED 100 shown has the same structure. (Reference) Figure 4 and Figure 5The light-emitting layer 520 is continuous between adjacent micro-LEDs 500a and 500b. The first type semiconductor layer 510 is also continuous between adjacent micro-LEDs 500a and 500b. The light-emitting layer 520 and the first type semiconductor layer 510 are continuously formed over the entire micro-LED panel. In some embodiments, the maximum width of the second type semiconductor layer 530 for each micro-LED is smaller than the minimum width of the first electrode 540 for each micro-LED. Each first electrode 540 is formed at the bottom of the first type semiconductor layer and is typically aligned with the corresponding second type semiconductor layer 530. Furthermore, an isolation structure 560 is formed between adjacent micro-LEDs 500a and 500b to prevent crosstalk between the adjacent micro-LEDs. Figure 5 As shown, an isolation structure 560 is disposed on the light-emitting layer 520, and the top surface of the isolation structure 560 is equal to or higher than the top surfaces of the microLEDs 500a and 500b, for example, the top surface of the second electrode 550 of each microLED. Each second electrode 550 is formed on top of a corresponding second type semiconductor layer 530.

[0028] Figure 6 This is a side cross-sectional view showing the structure of exemplary adjacent micro-LEDs 600a and 600b included in micro-LED panel 400, according to some embodiments of this disclosure. The structures of micro-LEDs 600a and 600b can be... Figure 2 The structure of the miniature LED200 shown is the same. (Reference) Figure 4 and Figure 6 The light-emitting layer 620 is continuous between adjacent micro-LEDs 600a and 600b. The first type semiconductor layer 610 is also continuous between adjacent micro-LEDs 600a and 600b. The light-emitting layer 620 and the first type semiconductor layer 610 are continuously formed over the entire micro-LED panel 400. The second type semiconductor layer 630 includes one or more stepped structures 631, 632. The sidewalls of stepped structure 631 and stepped structure 632 are not aligned. Each first electrode 640 is formed at the bottom of the first type semiconductor layer 610 and is generally aligned with the corresponding second type semiconductor layer 630. Each second electrode 650 is formed at the top of the corresponding second type semiconductor layer 630. In some embodiments, the maximum width of the first electrode 640 is less than or equal to the maximum width of the second electrode 650. Furthermore, an isolation structure 660 is formed between adjacent micro-LEDs 600a and 600b to prevent crosstalk between the adjacent micro-LEDs.

[0029] Figure 7 This is a structural diagram showing a plan view of an exemplary microLED chip 700 according to some embodiments of this disclosure. Figure 7 As shown, the micro LED chip 700 includes one or more micro LED display panels 710, each micro LED display panel having the above-mentioned reference. Figure 4 to Figure 6 The structure of the described micro LED panel

[0030] Note that, Figure 4 The number of micro-LEDs 410 in the 400 micro-LED panel, and Figure 7 The number of micro-LED panels 710 shown is for illustrative purposes only. In practice, the number of micro-LEDs in a micro-LED panel and the number of micro-LED panels in a micro-LED chip can vary.

[0031] In some embodiments, the light-emitting layer is formed of a quantum well layer. The thickness of the quantum well layer (i.e., the light-emitting layer) is less than the thickness of the first type of semiconductor layer. The thickness of the first electrode is greater than the thickness of the quantum well layer of the light-emitting layer, and the thickness of the second electrode is greater than the thickness of the quantum well layer of the light-emitting layer. The thickness of the second type of semiconductor layer is more than twice the thickness of the first type of semiconductor layer.

[0032] The microLED chip provided in this disclosure prevents carrier diffusion between adjacent microLEDs and forms a continuous quantum well effect at the sidewalls of the quantum well to minimize nonradiative recombination of surface carriers. Furthermore, the isolation structure formed between adjacent LEDs suppresses photoelectric crosstalk. Additionally, the minimum width of the first electrode is smaller than the minimum width of the first type of semiconductor layer, thereby reducing the carrier diffusion region.

[0033] It should be noted that relational terms in this document, such as “first” and “second”, are used only to distinguish an entity or operation from another entity or operation, without requiring or implying any actual relationship or order between these entities or operations. Furthermore, the words “comprising,” “having,” “containing,” and “including,” and other similar forms, are intended to be semantically equivalent and are open-ended; one or more items following any of these words do not imply an exhaustive list of such items or that the list is limited to only one or more items.

[0034] As used herein, unless otherwise expressly stated, the term "or" covers all possible combinations unless impractical. For example, if a database is declared to include A or B, then unless otherwise expressly stated or impractical, the database may include A, or B, or A and B. As a second example, if a database is declared to include A, B, or C, then unless otherwise expressly stated or impractical, the database may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C.

[0035] In the foregoing description, numerous specific details have been described, which may vary depending on the implementation. Certain modifications and alterations may be made to the described embodiments. Other embodiments will be apparent to those skilled in the art in light of the description and practice of the invention disclosed herein. The description and examples are intended to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims. The order of steps shown in the drawings is also intended for illustrative purposes only and is not intended to limit one to any particular order of steps. Therefore, those skilled in the art will understand that these steps may be performed in different orders while implementing the same method.

[0036] Exemplary embodiments have been disclosed in the accompanying drawings and description. However, many variations and modifications can be made to these embodiments. Accordingly, although specific terminology has been used, it is used only in a general and descriptive sense and not for limiting purposes.

Claims

1. A micro-LED, comprising: a first type semiconductor layer; a light emitting layer formed on the first type semiconductor layer; a second type semiconductor layer formed on the light emitting layer; wherein a bottom sidewall of the second type semiconductor layer is aligned with a sidewall of the first type semiconductor layer; and a sidewall of the second type semiconductor layer does not conform to a straight line; a thickness of the second type semiconductor layer is greater than twice a thickness of the first type semiconductor layer; a minimum width of the second type semiconductor layer is less than a minimum width of the first type semiconductor layer; a first electrode formed at a bottom of the first type semiconductor layer; and a second electrode formed at a top of the second type semiconductor layer; wherein a maximum width of the first electrode is less than or equal to a maximum width of the second electrode.

2. The micro-LED of claim 1, wherein, The sidewall of the second type semiconductor layer comprises at least one step.

3. The micro-LED of claim 2, wherein, A bottom width of a bottom step structure of the second type semiconductor layer is the same as a top width of the first type semiconductor layer.

4. The micro-LED of claim 2, wherein, A sidewall of the bottom step structure of the second type semiconductor layer is aligned with a sidewall of the light emitting layer.

5. The micro-LED of any one of claims 1-4, wherein, The sidewall of the first type semiconductor layer is aligned with a sidewall of the light emitting layer.

6. The micro-LED of any one of claims 1-4, wherein, The maximum width of the first electrode is less than a minimum width of the first type semiconductor layer.

7. The micro-LED of claim 6, wherein, The maximum width of the first electrode is less than or equal to a minimum width of the second electrode.

8. The micro-LED of claim 1, wherein, A maximum width of the second electrode is less than a bottom width of the second type semiconductor.

9. A micro LED panel comprising two or more micro LEDs according to any one of claims 1 to 8, wherein, The light emitting layer is continuous between adjacent micro-LEDs.

10. The micro-LED panel of claim 9, wherein, The light emitting layer is formed by a quantum well layer.

11. The micro-LED panel of claim 9 or 10, further comprising an isolation structure between the adjacent micro-LEDs.

12. The micro-LED panel of claim 9, wherein, The first type semiconductor layer is continuous between the adjacent micro-LEDs.

13. The micro-LED panel of claim 9, wherein, The first type semiconductor layer is discontinuous between the adjacent micro-LEDs.

14. A micro-LED chip comprising one or more micro-LED panels according to any one of claims 9 to 13.

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