A new Schottky-barrier GaAs epitaxial diode for infrared detection

While experimenting with Schottky-barrier diodes in this laboratory, an unusual I-V characteristic of a GaAs nn⁺epitaxial diode with Ni-Au contact was observed. The reverse characteristic is normal with a sharp breakdown voltage around 50 V. The forward clark characteristic shows no current until it breaks down at about 60 V. Under illumination, a large current flows at a forward voltage less than 1 V. The forward characteristic looks like that of an emission-saturated thermionic diode except that the saturation current increases drastically with illumination. This phenomenon is reproducible on all diodes fabricated on a certain wafer.