Uv Sensors Based on Polycrystalline Diamond

The performances of UV sensors based on CVD-diamond films with different structural and electronics properties are investigated in order to evaluate the material requirements for high UV sensitivity. Electrical and photoelectrical characterization of photoconductive metal-diamond-metal (MDM) planar structures have been evaluated and compared as a function of temperature between 300 and 600 K, under applied field strengths up to 10⁵ V/cm, in the spectral range 200-800 nm. Transient behaviour has been studied by using nanosecond laser pulses and very low frequency chopped light. Experimental data are presented and discussed in terms of trapping and recombination of photogenerated carriers. It is shown that sensors realized on large-grained thick diamond films exhibit responsivity values up to 20 mA/W at 220 nm, with more than four orders of magnitude UV-VIS discrimination near the diamond absorption edge even at high temperature.