Effect of different growth conditions on surface morphology and optical properties of CdTe/GaAs epitaxial films

CdTe(211)thin films are grown on GaAs(211)B substrates by molecular beam epitaxy(MBE), the influence of different process conditions on the surface morphology and optical properties of the CdTe epitaxial films are stemati-cally studied. The study shows that under certain growth temperatures, growing CdTe thin films in a Te atmosphere and increasing the CdTe and Te beam ratio can significantly reduce the size and density of pyramid defects on the CdTe sur-face. When the CdTe and Te beam ratio is 6. 5, the pyramid defects almost disappear, and the surface smoothness of the material is significantly improved. X-ray diffraction(XRD)also shows that the crystal quality of CdTe has significantly improved. Further Raman spectroscopy shows that with the increase of the CdTe and Te beam ratio, the A1 peak of Te weakens, and the intensity ratio of the CdTe LO and TO phonon peaks increases. Low-temperature photoluminescence (PL)studies also show that with the increase of the CdTe and Te beam ratio, the reduction of Cd vacancies can reduce the peak intensity of the deep energy level region related to impurity energy levels, while the half-width of the free exci-ton peak related to crystal quality reduces, and the optical quality of the material is significantly improved. This study explores the ideal process window and related mechanisms of CdTe/GaAs epitaxial materials, and provides a foundation for further epitaxial high-quality HgCdTe materials using this as a buffer layer.