Influences of screw dislocations on electroluminescence of AlGaN/AlN-based UVC LEDs

Dong Liu,Akhil R K Kalapala,Weidong Zhou,Baxter Moody,Sang June Cho,Jeongpil Park,Xudong Wang,Huilong Zhang,John D Albrecht,Zhenqiang Ma,Rafael Dalmau,Jiarui Gong,Corey R Carlos,Jisoo Kim

doi:10.1063/1.5108743

Abstract

We investigated two types of threading dislocations in high Al-composition Al0.55Ga0.45N/AlN multiple quantum well (MQW) structures grown on AlN substrate for electrically injected deep ultraviolet light-emitting diodes (LEDs). The surface morphology and defects electrical characteristics of the MQW LED structures were examined via conductive atomic force microscopy (CAFM). We found that the disparity between photoluminescence (PL) and electroluminescence (EL) spectra in terms of light emission output and wavelength shift are attributed to the existence of the surface hillocks, especially to the ones that have open-core dislocations. The open-core dislocations form current leakage paths through their defect states and the composition inhomogeneity (i.e., Ga rich) at the dislocation sites are responsible for the light emission at longer wavelengths.

Highlights

N scitation.org/journal/adv was used in lieu of p-type AlxGa1-xN to improve the hole concentration
We investigated two types of threading dislocations in high Al-composition Al0.55Ga0.45N/AlN multiple quantum well (MQW) structures grown on AlN substrate for electrically injected deep ultraviolet light-emitting diodes (LEDs)
The surface morphology and defects electrical characteristics of the MQW LED structures were examined via conductive atomic force microscopy (CAFM)

Summary

Introduction

N scitation.org/journal/adv was used in lieu of p-type AlxGa1-xN to improve the hole concentration. We investigated two types of threading dislocations in high Al-composition Al0.55Ga0.45N/AlN multiple quantum well (MQW) structures grown on AlN substrate for electrically injected deep ultraviolet light-emitting diodes (LEDs).

Results

Conclusion