| Summary: | 碩士 === 國立彰化師範大學 === 電子工程學系 === 97 === We present the optical and electrical characterization of undoped rhenium disulphide（ReS2）and gold-doped rhenium disulphide（ReS2：Au）which were grown by the chemical-vapor transport method（CVT）with I2 as the transport agent.
We present the polarization-dependent optical and electrical properties of ReS2 single crystals using temperature- and polarization- dependent optical absorption, reflectance, modulation spectroscopy, photoluminescence, electrical resistivity and photoconductivity measurements. Furthermore, the crystallinity was investigated by scanning electron microscopy. In optical measurements were used for studying the anisotropic optical properties of ReS2, in the temperature range from 20 to 300 K. The origin of these excitonic transitions can be investigated that using the basis of polarization selection rules.
Three excitonic transitions coming from different origins have been assigned as Eex1, Eex2, EexS. A prominent and enlarged feature of excitonic series Eexs positioned at higher energy side with respect to the previously identified band-edge excitons Eex1 and Eex2 in the PzR spectrum. The observed excitonic sequence has been shown to be corresponding to the Rydberg series starting with principal quantum number n = 2. Moreover, the least-squares fits are used to extract the parameters that describe the temperature variations of the band-edge excitonic transitions, and to identify the origin of the excitonic transitions. The intensity variation following the Malus’ law is a reasonable result, because the intensity of incident light at different polarization angles can be separated into two components (perpendicular or parallel to b axis). Comparatively with the PzR spectra of undoped ReS2, two extra transitions EexA and EexB due to the doping effects in ReS2：Au sample have been observed.
From the PC spectra, the exciton Eex3 contributes to the photoconductivity of ReS2：Au. The results indicate of photoconductivity that the σ∥ are smaller than the σ⊥ due to the axial dependency of the mobilities.
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