Improved Optical Properties of Nonpolar AlGaN-Based Multiple Quantum Wells Emitting at 280 nm

Jianguo Zhao,Zhe Chuan Feng,Tao Tao,Bin Liu,Xianjian Long,Daihua Chen,Jianhua Chang,Jiangyong Pan

doi:10.1109/jphot.2020.3039897

Abstract

The optical properties of nonpolar AlGaN multiple quantum wells (MQWs) emitting at 280 nm were investigated intensively using temperature-dependent and time-resolved photoluminescence spectra associated with the characterization of structural properties. The densities of superficial pits and basal-plane stacking faults (BSFs) were reduced by 33.8% and 35.9%, respectively, for nonpolar AlGaN MQWs due to the carefully optimized dual nitridation. It was found that the nonpolar MQWs emission can be significantly improved by reducing the BSFs density as the BSFs emission was the main competing channels. Moreover, an internal quantum efficiency of 39% for nonpolar Al0.43Ga0.57N MQWs at emission wavelength of 279 nm was achieved even the full width at half maximum values of X-ray rocking curves were 0.565° for c-direction and 0.797° for m-direction. This fact means that a highly efficient deep ultraviolet light sources can be expected by means of nonpolar AlGaN due to the elimination of quantum confined Stark effect induced the decrease in radiative lifetime.

Highlights

AlGaN-Based ultraviolet and deep-ultraviolet (DUV) light-emitting diodes (LEDs) are the promising semiconductor ultraviolet light sources due to the possibility of achieving efficient ultraviolet light emission from AlGaN-based multiple quantum wells (MQWs), the realizability of N- and P-type semiconductors in DUV spectral region, as well as the steady physical properties and long device lifetime [1]–[4]
An internal quantum efficiency of 39% for nonpolar Al0.43Ga0.57N MQWs at emission wavelength of 279 nm was achieved even the full width at half maximum values of X-ray rocking curves were 0.565° for c-direction and 0.797° for m-direction. This fact means that a highly efficient deep ultraviolet light sources can be expected by means of nonpolar AlGaN due to the elimination of quantum confined Stark effect induced the decrease in radiative lifetime
It was found that the basal-plane stacking faults (BSFs) emission was the main competing channels for nonpolar AlGaN-based MQWs, and a higher realizability of efficient deep ultraviolet light sources can be expected by means of nonpolar AlGaN than polar counterpart

Summary

Introduction

AlGaN-Based ultraviolet and deep-ultraviolet (DUV) light-emitting diodes (LEDs) are the promising semiconductor ultraviolet light sources due to the possibility of achieving efficient ultraviolet light emission from AlGaN-based multiple quantum wells (MQWs), the realizability of N- and P-type semiconductors in DUV spectral region, as well as the steady physical properties and long device lifetime [1]–[4]. The development of DUV LEDs was restricted due to the polarization electric field-induced quantum confined Stark effect (QCSE) [9] and the low hole injection efficiency resulted by low hole concentration of P-type AlGaN [1] Another alternative approach may be to utilize nonpolar AlGaN to achieve high-efficiency DUV LEDs. The extensive study on nonpolar group-III nitrides was started in 2000 and received much attention as the IQE can be highly improved for the irreplaceable advantage: short radiative lifetime and decreased competing nonradiative recombination due to the elimination of QCSE [10]. It was found that the BSFs emission was the main competing channels for nonpolar AlGaN-based MQWs, and a higher realizability of efficient deep ultraviolet light sources can be expected by means of nonpolar AlGaN than polar counterpart

Experimental

Results and Discussions

Conclusion