As-doped SnO2 thin films for use as large area position sensitive photodetector

The main purpose of this study is to obtain transparent and conductive As-doped SnO2 thin films and their application for large area position sensitive structure Si-SiO2-SnO2:As, acting on the base of lateral photoeffect. The films were deposited over n-type silicon substrate with native SiO2 surface by spray pyrolysis technique, using 0.25 M water-ethanol solution of SnCl4 consisting As2O5 as dopant. The films were characterized by X-ray diffraction; scanning electron microscopy and atomic force microscopy. Si-SiO2-SnO2:As structures were prepared and the lateral photoeffect was investigated. Under nonuniform irradiation with a laser beam, a lateral photovoltage (LPV) appeared, with high sensitivity to the spot position on the plane of the metal oxide film. The LPV depends on the conductivity and optical transmittance of the films. The position sensitivity shows a peak about 36 mV/mm for the films of SnO2 doped with As. The position characteristic shows good linearity and resolution and could be useful for practical applications.