X-ray diffraction study of the AgCd2−xMnxGaS4 semiconductor alloys and their electrical, optical, and photoelectrical properties

The AgCd2−xMnxGaS4 alloys were investigated by powder X-ray diffraction. The AgCd2−xMnxGaS4 solid solutions exist in the range of 0⩽x⩽1.24. The refinement of the AgCd0.8Mn1.2GaS4 crystal structure (Pmn21 space group, a=0.80768(3)nm, b=0.68105(2)nm, c=0.65203(2)nm, V=0.35866(4)nm3) has proved the isovalent substitution of Cd with Mn. The band gap energy of the solid solutions has been estimated from the intrinsic absorption edge at 300 K. Within the solid solutions range, the band gap increases from 2.15 eV for the AgCd2GaS4 composition to 2.4 eV for the AgCd0.8Mn1.2GaS4 composition. The spectral distribution of photoconductivity has been investigated for different compositions. The AgCd2−xMnxGaS4 alloys with x⩽0.30 exhibit the highest photosensitivity. The strong photoconductivity in the 600-610 nm region is attributed to the presence of cadmium vacancies or cadmium-containing complexes in the crystal structure, which act as the photoactive centers.