The investigation on strain relaxation and double peaks in photoluminescence of InGaN/GaN MQW layers

Abstract

Two emission peaks were observed in the low temperature photoluminescence (LTPL) spectra of an InGaN/GaN multiple quantum well (MQW) structure before and after nanopillar fabrication. After nanopillar fabrication it is found that among the two peaks the longer wavelength peak exhibits a clear blue shift and has a much stronger enhancement in LTPL intensity than the shorter one. Combined with x-ray diffraction and spatially resolved cathodoluminescence analyses, the difference induced by nanopillar fabrication is ascribed to different strain relaxation states in the lower and upper quantum well layers. It is found that the lower QW layers of the as-grown MQW which causes the longer wavelength PL peak are more strained, while the upper ones are almost fully strain-relaxed. Therefore, the nanopillar fabrication induces much less strain relaxation in the upper part of the MQW than in the lower one.

Microcathodoluminescence spectra evolution for planar and nanopillar multiquantum-well GaN-based structures as a function of electron irradiation dose

“…This is indeed happening in many MCL experiments. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] For InGaN/GaN multiple quantum well (MQW) LED structures, the effects of low energy electron beam irradiation (LEEBI) on optical properties, as detected by MCL, were studied in Refs. 6, 10, and 13-17.…”

Effects of quantum well number on spectral response of InGaN/GaN multiple quantum well solar cells

“…As is well known that strain relaxation in QW layers may play a negative role in optical properties . The photoluminescence (PL) and electroluminescence (EL) spectra of InGaN/GaN MQW solar cells thus are measured.…”

Exciton states and optical transitions in InGaN/GaN quantum dot nanowire heterostructures: Strong built-in electric field and dielectric mismatch effects

“…Due to recent progress in semiconductor nanowire growth, it became possible to grow nanowires with small diameters and large aspect ratio, which allowed for the fabrication of well controlled one-dimensional (1D) InGaN nanowires and the corresponding nanoscale InGaN/GaN heterostructures [7,[12][13][14][15]. The straight and helical InGaN core-shell nanowires were fabricated in a tube furnace by chemical vapor deposition [13].…”