InGaN/GaN Multi-Quantum-Well and Light-Emitting Diode Based on V-pit-Shaped GaN Grown on Patterned Sapphire Substrate

TL;DR

This study demonstrates that V-pit-shaped GaN structures grown on patterned sapphire substrates improve the performance of InGaN/GaN multi-quantum-well LEDs by enhancing strain relaxation and hole injection, leading to brighter emission.

Contribution

It introduces a method to grow regularly arranged V-pits on GaN on patterned sapphire, improving LED efficiency through structural and optical enhancements.

Findings

V-pits relax strain in InGaN quantum wells.

Enhanced hole injection observed around V-pits.

Dual emission peaks at 410 nm and 450 nm identified.

Abstract

V-pit-defects in GaN-based light-emitting diodes induced by dislocations are considered beneficial to electroluminescence because they relax the strain in InGaN quantum wells and also enhance the hole lateral injection through sidewall of V-pits. In this paper, regularly arranged V-pits are formed on c-plane GaN grown by metal organic vapor phase epitaxy on conventional c-plane cone-patterned sapphire substrates. The size of V-pits and area of flat GaN can be adjusted by changing growth temperature. Five pairs of InGaN/GaN multi-quantumwell and also a light-emitting diode structure are grown on this V-pit-shaped GaN. Two peaks around 410 nm and 450 nm appearing in both photoluminescence and cathodeluminescence spectra are from the semipolar InGaN/GaN multi-quantum-well on sidewalls of V-pits and cplane InGaN/GaN multi-quantum-well, respectively. In addition, dense bright spots can be observed on the surface of light-emitting diode when it works under small injection current, which are believed owing to the enhanced hole injection around V-pits.