In situ bow monitoring: towards uniform blue and green InGaN/GaN quantum well structures grown on 100 mm sapphire substrates by MOVPE

Abstract

AbstractIn this work, a home‐made curvature measurement tool is used to monitor the wafer bow evolution during epitaxy of blue‐green quantum well structures grown on 100 mm sapphire substrates. A single position detector is installed to real‐time record both the surface reflectance and the wafer bowing simultaneously. Due to the low thermal conductivity of sapphire, a very large wafer bow was observed during high temperature thermal annealing before growth. The large wafer bow may lead to non‐uniformity of both GaN buffer layers and InGaN/GaN multiple quantum wells (MQW). Careful temperature profile tuning and control of wafer bowing are critical to improve the layer uniformity. With the assistance of this in‐situ bow monitoring tool, uniform and high efficiency blue/green InGaN/GaN quantum well structures have been demonstrated on 100 mm sapphire substrates by Metal Organic Vapour Phase Epitaxy (MOVPE). The internal quantum efficiency (IQE) of the blue MQW structure is as high as 76%. This is deduced from temperature dependent (4 K‐300 K) and power dependent photoluminescence (PL) measurements. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)