Bias dependent spatially resolved photoluminescence spectroscopy and photocurrent measurements of InGaN/GaN LED structures

Abstract

The optical properties of Nitride-based quantum well devices are affected by internal fields, fluctuation of the composition of the quantum well and nonradiative recombination. In this paper, we present a method to separate these effects by optical spectroscopy and photocurrent measurements under varying applied bias. We observe long-range fluctuations both in the photoluminescence (PL) properties and the photocurrent, while fluctuations on the sub-mm length scale can only be observed in the PL. A comparison with simplified 1D calculations leads to the assumption, that the long-range fluctuations are caused by fluctuations of the quantum well width, while the short-range fluctuations are explained by a varying nonradiative recombination (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)