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Title: Effect of Deep Centers on Charge-Carrier Confinement in InGaN/GaN Quantum Wells and on LED Efficiency

Abstract

The deep-center-assisted tunneling of carriers in p–n structures of light-emitting diodes (LEDs) with InGaN/GaN quantum wells (QWs) makes smaller the effective height of the injection barrier, but leads to a dependence of the radiation efficiency on the density and energy spectrum of defects in GaN. In the case of hopping conduction across the space charge region, the forward voltage mainly drops near the QW boundary, where the density of deep states at the quasi Fermi-level is the lowest. As a result, band bending at the boundary decreases, and, with increasing current, the direction of the electric field also changes, which leads to a weaker confinement of holes, to their non-radiative recombination in the n barrier, and to an efficiency droop. The low efficiency of green GaN LEDs is associated with the dominance of deep centers and insufficient density of shallow centers in the energy spectrum of defects in barrier layers near the boundaries with the QW. The proposed model is confirmed by the stepwise experimental dependences of the current, capacitance and efficiency of green and blue LEDs in the case of forward bias, which reflect the contribution of color centers responsible for the defect photoluminescence bands in GaN.

Authors:
Publication Date:
OSTI Identifier:
22749878
Resource Type:
Journal Article
Journal Name:
Semiconductors
Additional Journal Information:
Journal Volume: 52; Journal Issue: 7; Other Information: Copyright (c) 2018 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1063-7826
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CHARGE CARRIERS; COLOR CENTERS; CONFINEMENT; DEFECTS; EFFICIENCY; ELECTRIC FIELDS; ENERGY SPECTRA; FERMI LEVEL; GALLIUM NITRIDES; LIGHT EMITTING DIODES; QUANTUM WELLS; SPACE CHARGE; TUNNEL EFFECT

Citation Formats

Bochkareva, N. I., and Shreter, Y. G., E-mail: y.shreter@mail.ioffe.ru. Effect of Deep Centers on Charge-Carrier Confinement in InGaN/GaN Quantum Wells and on LED Efficiency. United States: N. p., 2018. Web. doi:10.1134/S1063782618070035.
Bochkareva, N. I., & Shreter, Y. G., E-mail: y.shreter@mail.ioffe.ru. Effect of Deep Centers on Charge-Carrier Confinement in InGaN/GaN Quantum Wells and on LED Efficiency. United States. doi:10.1134/S1063782618070035.
Bochkareva, N. I., and Shreter, Y. G., E-mail: y.shreter@mail.ioffe.ru. Sun . "Effect of Deep Centers on Charge-Carrier Confinement in InGaN/GaN Quantum Wells and on LED Efficiency". United States. doi:10.1134/S1063782618070035.
@article{osti_22749878,
title = {Effect of Deep Centers on Charge-Carrier Confinement in InGaN/GaN Quantum Wells and on LED Efficiency},
author = {Bochkareva, N. I. and Shreter, Y. G., E-mail: y.shreter@mail.ioffe.ru},
abstractNote = {The deep-center-assisted tunneling of carriers in p–n structures of light-emitting diodes (LEDs) with InGaN/GaN quantum wells (QWs) makes smaller the effective height of the injection barrier, but leads to a dependence of the radiation efficiency on the density and energy spectrum of defects in GaN. In the case of hopping conduction across the space charge region, the forward voltage mainly drops near the QW boundary, where the density of deep states at the quasi Fermi-level is the lowest. As a result, band bending at the boundary decreases, and, with increasing current, the direction of the electric field also changes, which leads to a weaker confinement of holes, to their non-radiative recombination in the n barrier, and to an efficiency droop. The low efficiency of green GaN LEDs is associated with the dominance of deep centers and insufficient density of shallow centers in the energy spectrum of defects in barrier layers near the boundaries with the QW. The proposed model is confirmed by the stepwise experimental dependences of the current, capacitance and efficiency of green and blue LEDs in the case of forward bias, which reflect the contribution of color centers responsible for the defect photoluminescence bands in GaN.},
doi = {10.1134/S1063782618070035},
journal = {Semiconductors},
issn = {1063-7826},
number = 7,
volume = 52,
place = {United States},
year = {2018},
month = {7}
}