Correlation between strain, optical and electrical properties of InN grown by MBE

Abstract

The evolution of structural, optical and electrical properties was investigated for thin InN layers on either GaN or AlN buffer layers. Up to a layer thickness around 1 μm a biaxial strain is present in the layers. On AlN buffers the InN layers relax faster than on GaN. Both the interface and the surface affect the electron carrier concentration essentially. Thus, only with layers exceeding a thickness of 1 μm electron densities below 1018 cm−3 can be achieved. Optical spectroscopy indicates a band gap energy below 0.7 eV, however, the position of the absorption edge can be shifted up to 0.5 eV in thin layers. The Moss–Burstein shift due to the high electron concentration has the major influence on these effects. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)