Characterization of AgGaTe2 films deposited on KCl substrate

Silver gallium telluride (AgGaTe2) films were prepared by thermal evaporation technique in vacuum of the order of 10-5 Torr onto the KCl substrate kept at different temperatures. The experimental conditions are optimized to obtain better crystallinity of the films. These films have been studied for their structural, electrical and optical properties. X-ray diffraction observations reveal that crystallinity of films increases with increase in substrate temperature. Also, scanning electron micrographs show an increase in grain size, thus indicating formation of more ordered system at higher substrate temperature. The electrical conductivity, Hall coefficient and carrier concentration of AgGaTe2 films have been investigated in the temperature range 193-413 K. The films appear to be p-type, which indicate that holes are dominant charge carriers. The carrier concentration and Hall mobility of films increases with increase in substrate temperature while electrical resistivity decreases. Analysis of optical spectra of the films in the wavelength range 300-1100 nm show an allowed direct transition near the fundamental absorption edge in addition to a transition originating from crystal field split levels. (Authors)