Effect of electron blocking layers on the conduction and valence band profiles of InGaN/GaN LEDs

Simon Hammersley,Phil Dawson,Rachel A Oliver,Fabien C.‐P Massabuau,Martin Frentrup,Menno J Kappers,Colin J Humphreys

doi:10.1002/pssc.201510188

Simon Hammersley, Phil Dawson + Show 5 more

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https://doi.org/10.1002/pssc.201510188

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Abstract

AbstractIn this paper we investigate the effect of including an electron blocking layer between the quantum well active region and the p‐type layers of a light emitting diode has on the conduction and valence band profile of a light emitting diode. Two light emitting diode structures with nominally identical quantum well active regions one containing an electron blocking layer and one without were grown for the purposes of this investigation. The conduction and valence band profiles for both structures were then calculated using a commercially available Schrödinger‐Poisson calculator, and a modification to the electric field across the QWs observed. The results of these calculations were then compared to photoluminescence and photoluminescence time decay measurements. The modification in electric field across the quantum wells of the structures resulted in slower radiative recombination in the sample containing an electron blocking layers. The sample containing an electron blocking layer was also found to exhibit a lower internal quantum efficiency, which we attribute to the observed slower radiative recombination lifetime making radiative recombination less competitive. (© 2016 The Authors. Phys. Status Solidi C published by WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Highlights

Light emitting diodes (LEDs) containing InGaN/GaN quantum wells (QWs) are widely used when high efficiency light emission is required in the ultraviolet [1], blue [2] and green [3] regions of the spectrum
Low temperature (10 K) PL decay transients measured on both samples showed that across the PL emission spectrum the PL decay transient in the sample containing an electron blocking layer (EBL) was of the order 20% longer than that for the sample that did not contain an EBL
The 300 K PL IQE was measured for the two samples, finding that the sample containing an EBL exhibited a lower IQE, 26% compared to 38% for the sample that did not contain the EBL, suggesting that the modification of the PL decay transient has led to less competitive recombination at room temperature in the sample containing an EBL

Summary

Introduction

Light emitting diodes (LEDs) containing InGaN/GaN quantum wells (QWs) are widely used when high efficiency light emission is required in the ultraviolet [1], blue [2] and green [3] regions of the spectrum. 10% larger than in the sample without an EBL.

Results

Conclusion