Thickness and composition determination of MBE-grown strained multiple quantum well structures by x-ray diffraction

Abstract

We present a new approach to determine the thickness and composition of individual layers in molecular beam epitaxy (MBE) grown multiple quantum well (MQW) structures by double crystal X-ray diffraction. The mean perpendicular lattice constant (d(perpendicular)SL0) and the period (P) of the MQW structures are calculated from the zeroth satellite peak position and the satellite peak spacings respectively. The thickness and composition of the individual layers are found by combining the growth times of the individual layers with d(perpendicular)SL0 and P. MQW structures of the form GaAs/XGaAs (X equals group III elements) grown on GaAs substrates are used to derive the theory for this approach and two MQW samples in the GaAs/InxGa1-xAs system are studied as an example of this approach. The results for both samples are checked by dynamical simulation. The simulated x-ray rocking curves for both samples have excellent agreement with the corresponding experimental x-ray rocking curves. This approach may be applied to other MQWs structures with two layers where one is a binary and the other is a ternary which includes the binary, such as AlAs/AlxGa1-xAs. It is therefore a technique not only for characterizing device structures containing MQW's but also for calibrating group III fluxes in MBE systems.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.