Enhancing microstructure and device performance of InGaN quantum dot micro-LEDs through substrate off-cut angle modulation

InGaN quantum dots (QDs) are regarded as a compelling candidate material for the fabrication of high-quality GaN-based micro-LEDs. In this work, to study the impact of a sub-strate structure on InGaN QDs and QD-based micro-LEDs, GaN-on-sapphire substrates with off-cut angles toward the a-axis of 0.2 degrees, 0.4 degrees, and 0.7 degrees were utilized as templates for the fabrication of InGaN QDs and InGaN QDs-based micro-LEDs. Experimental results show that GaN tem-plate with 0.4 degrees off-cut angle exhibits the narrowest terrace width and enables InGaN QDs to be higher and more uni-form. The InGaN QD sample grown on 0.4 degrees substrate has a very small wavelength shift of 2.5 nm with temperature increasing and owns the longest photoluminescence peak wavelength implying the highest In content. Furthermore, electroluminescence (EL) spectra demonstrate that QD-based micro-LED array has excellent wavelength stability under various injection currents, and the stability can be improved further on a GaN template with narrower terraces. The results indicate that altering the terrace width of GaN template is a feasible scheme for improving the properties of GaN-based micro-LEDs.(c) 2023 Optica Publishing Group