Improved quality of plasma assisted MBE‐grown GaN/AlGaN quantum wells revealed by two‐wavelength excited photoluminescence

Abstract

Below-gap states in plasma assisted MBE-grown GaN/AlGaN quantum well (QW) structures have been studied by two-wavelength excited photoluminescence (PL). The decrease of the PL intensity with the addition of a below-gap excitation light source of 1.17 eV implies the presence of an energy-matched below-gap state. We have studied several QW structures grown on AlGaN or AlN buffer layers on sapphire substrates. We found improved internal quantum efficiency with increasing the number of QW's and with providing a sufficiently thick AlGaN or AlN buffer layer. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)