Thermally stable visible-blind diamond photodiode using tungsten carbide Schottky contact

We have developed a thermally stable, deep-ultraviolet (DUV) photodiode using tungsten carbide (WC) Schottky and Ti/WC ohmic contacts for a boron-doped homoepitaxial p-diamond epilayer. Effects of thermal annealing in an argon ambient on the electrical and photoresponse properties were investigated. Annealing at temperatures up to 550 degrees C improves the rectifying current-voltage characteristics, resulting in a dramatic enhancement of DUV responsivity at 220 nm by a factor of 4 x 10(3). A blind ratio as large as 105 between DUV and visible light has been achieved at a reverse bias as small as 1 V. Development of the thermally stable WC-based Schottky and ohmic contacts provides a route for stable operation of a diamond photodetector at high temperatures. (c) 2005 American Institute of Physics.