Photovoltaic Schottky ultraviolet detectors fabricated on boron-doped homoepitaxial diamond layer

A photovoltaic diode using tungsten carbide (WC) Schottky contact for deep ultraviolet (DUV) light detection is developed using a lightly boron-doped homoepitaxial diamond layer. The photodiode shows a quick dc response time lower than an instrumental time constant of 0.3 s. The responsivity varies linearly with the DUV light intensity. A discrimination ratio of 10(5) between 210 nm and visible light is achieved at zero bias. The short-circuit photocurrent at 220 nm decreases with increasing the temperature from 300 to 373 K, whereas the Schottky barrier height under illumination remains unchanged. Numerical and experimental analyses reveal that the interface states between diamond and WC play a major role in reducing the zero-bias responsivity at elevated temperatures. (c) 2006 American Institute of Physics.