Investigation of the Surface and Interfacial Properties of Polycrystalline CdTe/Monocrystalline Si Structure

In this work, CdTe polycrystalline thin film was deposited on p-type monocrystalline Si substrate via magnetron sputtering technology without an oxygen portion using a well-designed post-processing method under N₂:O₂ = 4:1, and then CdTe films were etched on the Si surface by Br₂-CH₃OH solution to analyze the surface and interfacial characteristics of CdTe/Si such as structure, morphology, optics interdiffusion, and intermediate compounds. X-ray diffraction (XRD) results indicate that the polycrystalline CdTe grow preferentially in the (111) direction, and Raman data demonstrate that the CdTe thin film is rich in tellurium, meaning that CdTe, as a p-type semiconductor material, combined with p-Si to form a composite structure. Meanwhile, photoluminescence (PL) spectra suggest that p-CdTe/p-Si under high thermal processing can effectively remove ~1.40 eV defect level, which indicates that the CdTe layer has a lower recombination center. It is particularly worth mentioning that x-ray photoelectron spectroscopy (XPS), XRD, and Raman analysis confirm the Te–Si intermediate compounds at the CdTe/Si interface, which is very conducive to optimizing the contact characteristics of CdTe/Si, thereby improving the interfacial properties of CdTe/Si. This work reveals a potentially effective way to improve the performance of photoelectric devices by introducing poly-CdTe/Si as a composite structure.