Gallium arsenide (GaAs) thin films have been deposited on ITO-coated glass
substrates from acid aqueous solution by electrodeposition technique. The
structure and the morphology of the samples were analyzed by X-ray
diffraction (XRD) and atomic force microscope (AFM). The optical
characteristics were investigated at room temperature using a UV-Vis
spectrometer. At lower deposition time, the XRD patterns exhibit a mixture
of both cubic and orthorhombic GaAs phases. With further increase of the
film thickness, only orthorhombic structure was observed with a preferred
(100) orientation. By applying the Debye-Scherrer method, the estimated
crystallite size for the (200) orientation ranged from 30 to 50 nm, whereas
for the (022) orientation was found to be 13–22 nm. From the AFM
measurements, the rms surface roughness ranged between 11.4 and 18.4 nm. The
analysis of the optical absorption data of the annealed GaAs film deposited
at different times revealed direct band gap energy in the range of 1.60–1.85 eV. The large blueshifts observed in this study can be fully explained by
the Burstein-Moss effect.