Lattice stability and elastic evolution of CdTe membranes fabrication using III–V heterostructures as a substrate

Abstract

CdTe is a key binary compound for II–VI semiconductor systems since the precise control of its growth over different semiconductor materials of different orientations provides a general roadmap for telluride compounds, ranging from optically active layers to diluted magnetic semiconductors and topological insulators. The precise understanding of its epitaxy, film orientation and built-in strain is crucial for II–VI layer integration with commercial hosting substrates used for the latest semiconductor process nodes such as Si and GaAs. In this work, we show that it is feasible to use CdTe:GaAs/InGaAs/GaAs released membranes yielding high-quality crystalline layers. A combination of Raman scattering and X-ray diffraction results provide a concise scenario of evolution along different growth stages. Surface roughness and contact potential are evaluated by atomic force and Kelvin-probe microscopy, respectively. The coexistence of faceting types (001) and (111) becomes clear using AFM and KPFM near the edge of a CdTe membrane. At such edges the local cleavage of the membrane is probed, exposing several layer steps and reflecting the growth history of CdTe. In this condition, KPFM clearly differentiates faceting (throughout contact potential difference) more accurately than height profiles, allowing a qualitative explanation of the nucleation evolution in our system. Finally, the occurrence of a 4% in-plane interfacial compressive strain is observed by nanomembrane release and modelling with finite element methods. The results showing the flexibility of high-quality CdTe layers here can improve optoelectronic integration of II-VI semiconductors.