Effects of Laser Excitation and Temperature on Ag/GaSe_0.5S_0.5/C Microwave Filters

Abstract

The effects of temperature, illumination, and microwave signals on Ag/GaS_0.5S_0.5/C Schottky-type microwave filters have been investigated. The devices, which were produced from thin layers of GaSe_0.5S_0.5 single crystal, had room temperature barrier height and ideality factor of 0.65 eV and 3.28, respectively. Barrier height increased uniformly with increasing temperature, at 2.12 × 10⁻² eV/K, and the ideality factor approached ideality. The devices can even function at 95°C. A current switching phenomenon from low to high injection (“On/Off”) was also observed; this current switching appears at a particular voltage, V _s, that shifts toward lower values as the temperature is increased. When the devices were reverse-biased and illuminated with a laser beam of wavelength 406 nm, a readily distinguishable V _s was observed that shifted with increasing laser power. When the devices were run in passive mode and excited with an ac signal of power 0.0–20.0 dBm and frequency 0.05–3.0 GHz they behaved as band filters that reject signals at 1.69 GHz. Device resistance was more sensitive to signal amplitude at low frequencies (50 MHz) than at high frequencies. The features of these Ag/GaS_0.5S_0.5/C Schottky devices imply that they may be used as optical switches, as self standing, low band-pass, band reject filters, and as high band-pass microwave filters.