Properties of GaAs films deposited by pulse periodic technique

GaAs is a III-V compound possessing high mobility and a direct band gap of 1.43 eV , making it a very suitable candidate for photovoltaic applications. Thin GaAs films were prepared at room temperature by plating an aqueous solution containing GaCl₃ and As₂O₃ at a pH of 2. The current density was kept as 50 mA cm⁻² and the duty cycle was varied in the range 10–50%. The films were deposited on titanium and tin oxide coated glass substrates. Films exhibited polycrystalline nature with peaks corresponding to single phase GaAs. Optical absorption measurements indicated a direct band gap of 1.40 eV. The surface roughness of the films varied from 3 nm to 6 nm as the duty cycle increased. Raman spectra indicated both the LO and TO phonons for the films deposited at duty cycles above 25%. Photoelectrochemical studies indicated that the current and voltage output are higher than earlier reports on thin film electrodes.