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

Abstract

In 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)

Cathodoluminescence as an effective probe of carrier transport and deep level defects in droop-mitigating InGaN/GaN quantum well heterostructures

“…An alternative mechanism is electron beam-induced magnesium (Mg) activation in the p-GaN resulting in progressively increased wavefunction overlap within active region. 38) However, the low forward voltage of our LEDs (<3.0 V at 44 A cm −2 ) indicates that the p-n junction voltage is not expected to change much with further Mg activation. Furthermore, in a scenario in which radiative recombination is limited by Mg activation, little to no CL emission would be expected from the sample lacking a p-GaN capping layer, contrary to our observations (supplementary Fig.…”