High resolution x-ray analysis of pseudomorphic InGaN/GaN multiple quantum wells: Influence of Si doping concentration

Abstract

We report the structural properties of InGaN/GaN/AlGaN multiple quantum wells (MQWs) by means of two-dimensional reciprocal space mapping (RSM) of high resolution x-ray diffraction. The influence of Si doping in GaN barriers on the characteristics has been studied for 12-period MQWs grown by metalorganic chemical vapor deposition, which have different Si doping concentrations in the GaN barriers ranging from 1 X 10(17) to 3 X 10(19) cm(-3). Information on the structural quality of these MQWs was extracted from the linewidth broadening of the higher-order superlattice satellite peaks, as well as from the presence of Pendellosung oscillations. The measured diffraction curves were modeled using kinematic diffraction theory. From the symmetric and asymmetric RSMs around (0002), (0004) and (11 (2) over bar 4) reflections, we found that the InGaN/GaN/AlGaN MQWs are grown coherently on the GaN base layer. Better interface properties are achieved with Si doping. Our results indicate that Si doping in the GaN barriers affects the interface quality of the InGaN/GaN MQW systems, and thus, also influences the optical properties. (C) 1999 American Institute of Physics. [S0021-8979(99)02605-5].