Electrodeposition of wide band gap InGaxSyOz thin films for solar cell applications

Indium-Gallium-sulfide-oxide thin films were deposited onto F-doped SnO₂-coated glass by electrochemical deposition from an aqueous bath. The films were deposited at three different ratios of gallium to indium in the precursor bath; namely Ga/In] = 2/8, 5/5 and 8/2. The impact of the gallium content on the composition, optical transmission, structure, photosensitivity, electrical resistivity and morphology of the deposited films was investigated. The films deposited at Ga/In] = 5/5 and 8/2 had an energy gap as high as 3.5 eV. The X-ray diffraction spectrum of the film deposited at Ga/In] = 2/8 contained weak peaks of indium metal, but the In peaks were absent in the spectra of the films deposited at Ga/In] = 5/5 and 8/2. The photosensitivity of the film was observed by means of photoelectrochemical measurements, which confirmed that all the films showed n-type conduction. Finally, the film has been used as a buffer layer to fabricate a SnS-based thin film solar cell.