Assessment of the structural quality of CdTe/Cd1−xZnxTe strained superlattices by high-resolution x-ray diffraction and photoluminescence studies

We present a detailed analysis of x-ray double-diffraction rocking-curve measurements and low-temperature photoluminescence spectroscopy of (001) CdTe-CdxZn1−xTe strained-layer superlattices grown by molecular-beam epitaxy. The presence of very sharp satellite reflections demonstrate smooth interfaces with a well-defined modulation of both composition and perpendicular stress. Using a kinematical step model, the thickness, strain, and composition of the wells and the barriers are extracted. It is shown that fluctuations of 1 monolayer of the average period can be reproducibly obtained in such superlattices, in excellent agreement with the in situ reflection of high-energy electron diffraction oscillations measurements. The structural perfection of these superlattices is confirmed by the optical spectra which exhibit sharp excitonic transitions.