Characterization of the microstructures and optical properties of CdTe(0 0 1) and (1 1 1) thin films grown on GaAs(0 0 1) substrates by molecular beam epitaxy

Abstract In this work, CdTe(0 0 1) and CdTe(1 1 1) single-crystal films were successfully grown on GaAs(0 0 1) substrates by molecular beam epitaxy. By changing the nucleation temperature, CdTe(0 0 1) and (1 1 1) films could be controllably grown on the GaAs(0 0 1) substrates. The CdTe(0 0 1) and (1 1 1) films were grown via low-temperature nucleation followed by high-temperature growth. To optimize the quality of CdTe(0 0 1) films, a CdTe/ZnTe superlattice was used to reduce the lattice mismatch, and the CdTe(0 0 1) film was grown under a cadmium-rich atmosphere. The average surface roughness of the CdTe(1 1 1) and CdTe(0 0 1) films produced was approximately 0.76 nm and 1.37 nm, respectively. The epitaxial relationship between the CdTe(1 1 1) film and the GaAs(0 0 1) substrate was studied based on X-ray diffraction pole figures. The crystal quality of the CdTe(1 1 1) film was also characterized by X-ray diffraction and etch pit density. Finally, photoluminescence spectroscopy was used to investigate the crystal quality of CdTe(0 0 1) and (1 1 1). When the CdTe(0 0 1) film was grown under a cadmium atmosphere and using ZnTe as a buffer layer, the X-ray diffraction peak around 1.56 eV disappeared; this can be related to cadmium vacancies.