Open AccessMicroscopic origin of thermal droop in blue-emitting InGaN/GaN quantum wells studied by temperature-dependent microphotoluminescence spectroscopy
Author(s) -
Ryota Ishii,
Yuji Koyama,
Mitsuru Funato,
Yoichi Kawakami
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.428421
Subject(s) - materials science , voltage droop , dislocation , light emitting diode , optoelectronics , indium gallium nitride , gallium nitride , epitaxy , photoluminescence , spectroscopy , wide bandgap semiconductor , optics , layer (electronics) , composite material , physics , quantum mechanics , voltage , voltage divider
To elucidate the microscopic origin of the thermal droop, a blue-emitting indium gallium nitride (InGaN) quantum well grown on epitaxially laterally overgrown gallium nitride was investigated using temperature-dependent microphotoluminescence spectroscopy. Below 300 K, the sample exhibited a well-known dislocation-tolerant luminescence behavior. However, as temperature increases from 300 K to 500 K, the near band-edge emission at the wing region (with lower threading dislocation densities) was stronger than that at the seed region (with higher threading dislocation densities), indicating that threading dislocations are the microscopic origin of the thermal droop. Considering the carrier diffusion length, edge-type threading dislocations should play a major role in the thermal droop of heteroepitaxially grown InGaN-based LEDs.