Spray pyrolysis of CuGaxIn1-xSe2 thin films - electrical and optical properties

Polycrystalline, single phase thin films of CuGa_xIn_1–xSe₂ have been prepared by spray pyrolysis on glass substrates at temperatures, in the range 300 – 350°C. All the films were p-type and the resistivity varied from 40 to 3000 Ω-cm with a change in the gallium concentration. Change of the Hall mobility and free carrier concentration with gallium composition were also observed. The temperature dependence of electrical conductivity exhibited two activation energies. The optical studies showed that the films were highly absorbing with α >10⁴ cm⁻¹. The absorption edge was shifted towards higher energies with increasing gallium concentration and the fundamental energy band gap of the films varied from 1.02 to 1.69 eV.