Molecular beam epitaxial growth and physical property studies of CdSeTe for novel solar cells

• Main Authors: Hsiao-Hua Wang, 王孝華
• Other Authors: Jyh-Shyang Wang
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/31334772959610535603

碩士 === 中原大學 === 物理研究所 === 99 === We grew CdSe epilayers on GaSb and GaAs substrates by using plasma-assisted molecular beam epitaxy. Atomic force microscopy (AFM), low-temperature photoluminescence (LTPL) and X-ray diffraction (XRD) were employed to investigate the surface morphology, optical properties and lattice structure of CdSe epilayers, respectively. Though considerable Ga droplets on GaSb substrates were observed when thermal deoxidization was used without Sb flux supplied, the cubic CdSe epilayer was successfully grown on the thermal deoxidized GaSb substrate by using a Cd-rich CdSe buffer layer. However, we observed the CdSe epilayer prefer to form the hexagonal crystal structure under Cd-rich conditions. In the case of grown on GaAs substrates, we found the quality of CdSe epilayer was significantly improved by introducing a small amount of Te atoms. From the results of LTPL, AFM and XRD, we think that the Te atoms play the role of the surfactants in the CdSe epitaxial growth. Furthermore, the peak positions and their transition mechanisms in the LTPL spectrum of CdSe epilayer were investigate by temperature-dependent and power-dependent PL measurements. Besides, the native oxide of GaSb substrate was successfully removed and an atomic flat surface was obtained by using the hydrogen plasma source.