Growth and characterization of In-doped and undoped CuAlS2 single crystals

• Main Authors: Ping-Chen Chi, 紀秉辰
• Other Authors: Ching-Hwa Ho
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/82672355740815334099

碩士 === 國立東華大學 === 材料科學與工程學系 === 97 === Single crystals of In-doped and undoped CuAlS2 were grown by chemical vapor transport method using ICl3 as a transport agent. X-ray diffraction measurements confirmed chalcopyrite phase of the as-grown crystals. The crystslinity was investigated by scanning electron microscopy (SEM) and X-ray diffractometor (XRD) measurements. Optical property of CuAlS2 was characterized using thermoreflectance (TR) and photoluminescence (PL) techniques. Temperature-dependent TR measurements were carried out in a wide energy range of 3.2 to 6 eV between 35 and 340 K. The direct band gap of CuAlS2 was determind to be 3.6 ± 0.002 eV at 35 K. Six interband transition features can be detected in the TR spectra of CuAlS2 at low temperature. The energies and broadening parameters of CuAlS2 are analyzed by detailed line-shape fits to the TR spectra. Defect and band-edge emission of CuAlS2 were found in the temperature-dependent PL spectra in the energy range of 1.5 to 4.4 eV between 35 and 340 K. The emission near 3.3 eV is inferred to be a defect luminescence by sulfur vacancy, whereas the PL signal near 2.0 eV correlates with oxygen impurity. Temperature dependences of the interband transition features of CuAlS2 are analyzed and discussed.