Realization of III-Nitride c-Plane microLEDs Emitting from 470 to 645 nm on Semi-Relaxed Substrates Enabled by V-Defect-Free Base Layers

Cheyenne Lynsky,David Sotta,Stacia Keller,Michel Khoury,Matthew S. Wong,Steven P. DenBaars,Shuji Nakamura,Hongjian Li,Michael Iza,Ryan C. White

doi:10.3390/cryst11101168

Cheyenne Lynsky, David Sotta

Open Access

https://doi.org/10.3390/cryst11101168

Copy DOI

Abstract

We examine full InGaN-based microLEDs on c-plane semi-relaxed InGaN substrates grown by metal organic chemical vapor deposition (MOCVD) that operate across a wide range of emission wavelengths covering nearly the entire visible spectrum. By employing a periodic InGaN base layer structure with high temperature (HT) GaN interlayers on these semi-relaxed substrates, we demonstrate robust μLED devices. A broad range of emission wavelengths ranging from cyan to deep red are realized, leveraging the indium incorporation benefit of the relaxed InGaN substrate with an enlarged lattice parameter. Since a broad range of emission wavelengths can be realized, this base layer scheme allows the tailoring of the emission wavelength to a particular application, including the possibility for nitride LEDs to emit over the entire visible light spectrum. The range of emission possibilities from blue to red makes the relaxed substrate and periodic base layer scheme an attractive platform to unify the visible emission spectra under one singular material system using III-Nitride MOCVD.

Highlights

The use of GaN/InGaN material systems has been generally applied to light emitting diodes (LEDs) and blue laser diodes (LDs) and widely employed in many technologies, from general illumination to display and high-speed communications [1]
Compared to previous devices grown on lower quality base layers, we enabled long-wavelength electroluminescence, showing significant increase in the emitted light intensity and achieving working μLED devices
We report on fully eliminating the V-defects in the InGaN base layers originating in the substrates through periodically growing high temperature (HT) GaN interlayers under partial H2 carrier gas injection in the InGaN base layer, leading to significant structural improvement [18]

Summary

Introduction

The use of GaN/InGaN material systems has been generally applied to light emitting diodes (LEDs) and blue laser diodes (LDs) and widely employed in many technologies, from general illumination to display and high-speed communications [1]. Despite highly efficient devices in the blue emission regime, devices emitting at longer wavelengths such as green, yellow, amber, and red all suffer from much lower quantum efficiencies [2]. One of the most significant issues with these longer wavelength devices is incorporating indium in alloy compositions greater than 25% without serious microstructural degradation. The low structural quality of high-In alloy compositions makes the realization of these longwavelength emitters difficult [3,4]. The crystal quality of the alloy suffers with increasing. In content due to a variety of issues, notably the large difference between desorption temperature of In and Ga and significant and increasing lattice mismatch between the underlying GaN buffer layer and the InGaN quantum wells (QWs) [5].

Methods

Results

Discussion

Conclusion