Properties of MOCVD GaN/AlGaN heterostructures grown on polar and non‐polar bulk GaN substrates

Abstract

AbstractIn this work we present structural, optical and electrical properties of GaN epilayers and AlGaN/GaN MOCVD heterostructures obtained on polar and non‐polar 10x10 mm2, 1 and 1.5 inch bulk ammonothermal GaN substrates. The results were obtained based not only on a single‐point measurement but also on mapping across the sample area. In contactless electroreflectance (CER) spectra CER resonances related to optical transitions between excited states were clearly observed for GaN/AlGaN QWs grown on c ‐plane GaN substrates, whereas such features were not noted in the case of GaN/AlGaN QWs grown on m ‐plane GaN substrates. This experimental result clearly shows that the polarization‐related electric field leads to the quantum confinement of some extra states in the polar QW system. To check the advantage of homo‐epitaxy using ammonothermal GaN, high electron mobility transistors (HEMTs), and light emitting diodes (LEDs) structures were grown on (0001) Ga‐polarity, semi‐insulating and conductive GaN substrates respectively (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)