Optical characterization of III-VI GaSe1-xSx series layered semiconductors

• Main Authors: Chao-Hung Cheng, 鄭照煌
• Other Authors: Ching-Hua Ho
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/84954125011416706760

碩士 === 國立東華大學 === 材料科學與工程學系 === 92 === In this study, crystals of GaSe1-xSx layer compounds with x = 0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1 were grown by vertical Bridgman method. The crystallinity was investigated by X-Ray and SEM measurements . Optical property for GaSe1-xSx series layered semiconductors were evaluated by using the optical techniques of transmission and piezoreflectance measurements. The PzR spectra are fitted to a Lorentzian line-shape function appropriate for excitonic transitions to obtain transition energy and broadening parameter. Broader PzR line shape of the intermediate compositions than the binary GaSe compound indicates the presence of stronger alloy scattering effect in the ternary GaSe1-xSx layers. The absorption edge of GaSe1-xSx were examined by transmission measurement. The compositional dependence of the direct band gaps and band-to-band transition of GaSe1-xSx can be fitted by the expression of E(x) = E(0) + bx + cx2. According to the fits, the fitting parameters are determined to be. EA1(300K)(x)=1.986+0.62x+0.26x2 EA1 (15K) (x)=2.111+0.68x+0.37x2 EA4(300K)(x)=4.513+1.99x－1.02x2 EA4 (15K) (x)=4.691+1.54x+0.80x2