Nonradiative recombination-Critical in choosing quantum well number for InGaN/GaN light-emitting diodes
Author(s)
Date
2015Source Title
Optics Express
Print ISSN
10944087
Publisher
Optical Society of American (OSA)
Volume
23
Issue
3
Pages
A34 - A42
Language
English
Type
ArticleItem Usage Stats
215
views
views
161
downloads
downloads
Abstract
In this work, InGaN/GaN light-emitting diodes (LEDs) possessing varied quantum well (QW) numbers were systematically investigated both numerically and experimentally. The numerical computations show that with the increased QW number, a reduced electron leakage can be achieved and hence the efficiency droop can be reduced when a constant Shockley-Read-Hall (SRH) nonradiative recombination lifetime is used for all the samples. However, the experimental results indicate that, though the efficiency droop is suppressed, the LED optical power is first improved and then degraded with the increasing QW number. The analysis of the measured external quantum efficiency (EQE) with the increasing current revealed that an increasingly dominant SRH nonradiative recombination is induced with more epitaxial QWs, which can be related to the defect generation due to the strain relaxation, especially when the effective thickness exceeds the critical thickness. These observations were further supported by the carrier lifetime measurement using a pico-second time-resolved photoluminescence (TRPL) system, which allowed for a revised numerical modeling with the different SRH lifetimes considered. This work provides useful guidelines on choosing the critical QW number when designing LED structures. © 2014 Optical Society of America.
Keywords
Carrier lifetimeEfficiency
Quantum efficiency
Semiconductor quantum wells
Carrier lifetime measurements
Effective thickness
External quantum efficiency
Ingan/gan lightemitting diodes (LEDs)
Non-radiative recombinations
Numerical computations
Shockley read halls
Time-resolved photoluminescence
Light emitting diodes