The Growth Pits Filling Mechanism of CdZnTe Epitaxial Film Prepared by Close-Spaced Sublimation Based on the First-Principles Calculation

The preparation of high quality II-VI semiconductor single crystal still is a challenging task. The II-VI ternary compound Cd_1-xZn_xTe is an outstanding candidate for room temperature nuclear radiation detectors. Therefore, the epitaxial mechanism of its film is profound to clarify for accurate growth regulation and quality improvement. However, determining the essence of epitaxial growth remains challenge only using experiments to explore the effects of growth conditions on film epitaxy. In this work, the growth pits filling mechanism of CdZnTe epitaxial film has been elucidated by combining the experimental results with the first-principles calculation. Based on the Atomic Force Microscope data, the structural characteristics of growth pits were analyzed, and the layered growth model and the lateral step growth model were proposed. According to Gibbs-Wulff crystal growth law, the stability of two growth pits filling models was compared through the first-principles simulations. By comparing surface energies, we identified that the filling process of growth pits relies on the movement of steps along the interface. These results well describe the deposition mechanism of CdZnTe film prepared by close-spaced sublimation and provide inspirations to accurately regulate the II-VI film growth and obtain high quality films.