Photoconductive SnO2 Thin Films from Thermal Decomposition of Chemically Deposited SnS Thin Films

A method is described for the conversion of chemically deposited thin films of on glass substrates to . The method involves heating in air for 1 h at 400°C. The films have a thickness of ∼0.7 μm and appear black in reflected daylight but deep red in transmission. They are prepared by chemical deposition from homogeneous solutions for a period of 7 h 30 min at 60°C. Their conversion to is established by measurement of the optical transmittance and the x‐ray diffraction patterns. Both the and films display photoconductive properties. The dark and photoconductivities of the latter can be increased by ∼10 4 (to ∼1 Ω −1 cm −1 ) by vacuum annealing at 200°C for 1 h subsequent to thermal decomposition in the air. The increased photoconductivity is attributed to oxygen desorption from the grain boundaries and a non‐stoichiometry brought about during the vacuum annealing. This explanation is offered because subequent air‐annealing at 200°C is accompanied by a decrease in the conductivity.