Abstract
In this work, arrays of predominantly relaxed InGaN platelets with indium contents of up to 18%, free from dislocations and offering a smooth top c-plane, are presented. The InGaN platelets are grown by metal–organic vapor phase epitaxy on a dome-like InGaN surface formed by chemical mechanical polishing of InGaN pyramids defined by 6 equivalent {101̅1} planes. The dome-like surface is flattened during growth, through the formation of bunched steps, which are terminated when reaching the inclined {101̅1} planes. The continued growth takes place on the flattened top c-plane with single bilayer surface steps initiated at the six corners between the c-plane and the inclined {101̅1} planes, leading to the formation of high-quality InGaN layers. The top c-plane of the as-formed InGaN platelets can be used as a high-quality template for red micro light-emitting diodes.
Highlights
Self-emissive displays based on red, green, and blue micro light-emitting diodes (LEDs) are drawing increasing attention.While micro-LEDs made of nitride semiconductors are chosen for green and blue colors, red micro-LEDs form a bottleneck for large-scale display applications.[1]
>35%, respectively) which are important for ultrahigh resolution and high brightness display applications based on micro-LEDs, high-quality InGaN layers with indium contents well above 5% are clearly needed as a buffer layer
This is in agreement with what we found in our previous work, where the c-plane was formed by high-temperature annealing of InGaN pyramids.[27]
Summary
Self-emissive displays based on red, green, and blue micro light-emitting diodes (LEDs) are drawing increasing attention. Compared with our previous work on InGaN platelets where dislocations were formed because of the large indium content discontinuity between different layers,[27] the direct InGaN growth on the CMP-formed InGaN templates with similar indium contents completely eliminates the formation of dislocations Such high-quality InGaN platelets can be used as templates to grow green and red LEDs on the top c-plane with improved lattice match between the templates and InGaN QWs. The InGaN pyramids were grown selectively on substrates of GaN/sapphire from 100 to 200 nm large openings in a SiNx mask by MOVPE (Figure 1a) Such InGaN pyramids, defined by 6 equivalent {101̅1} planes, were realized with an indium content of up to 20% (PL peak around 2.48 eV at RT).[26] In order to prevent the pyramids from being detached during the CMP, a layer of SiOx was deposited on the samples by plasma-enhanced chemical vapor deposition (Figure 1b). PL decay was measured using a streak camera having a temporal resolution of around 2 ps
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