Wavelength modulation optical spectra of Ag3AsS3 crystals in the energy gap

Absorption spectra of Ag3AsS3 single crystals in E||c and E⊥c polarizations were investigated at temperatures 10 and 300 K. The edge absorption temperature dependence was analyzed in temperature range 300 - 10 K in E⊥c and E||c polarizations. Transmission spectra in crossed polarizers for single crystal plates with different thicknesses were studied. Indirect energy intervals (Eg1ind. and Eg2ind.) for both polarizations were found out in wavelength modulation transmission spectra (ΔT/Δλ) measured at 10 K. In photoluminescence spectra at 11 K an emission maximum associated with indirect excitonic transitions was discovered. Temperature dependences of photoconductivity of Au–Ag3AsS3–Au structure were researched.