UV-induced photoconduction in diamond

Owing to its physical properties, diamond is a very promising candidate for UV photon detection. The synthesis of very high quality polycrystalline diamond thick films and single crystals is presently accomplished routinely using the chemical vapour deposition (CVD) technique. Metal/diamond/metal ohmic junctions are produced by depositing electrical contacts on the front surface (coplanar contacts) or on both front and back (sandwich contacts). The investigation of diamond properties in the wavelength range 100-300 nm is of considerable interest in order to attain ultraviolet (UV) detectors having high quantum efficiency against no sensitivity to visible photons, along with radiation hardness and chemical inertness. Improvements in diamond synthesis techniques and processing technology now make available very high quality polycrystalline diamond films as well as optical-grade single crystals with dimensions sufficiently large for developing detectors. Several problems limiting the performance have been solved, and single-pixel detectors are close to being suitable for exploitation. This paper reviews the status of the art of diamond-based UV detectors, their application in specific fields, such as excimer lasers, photolithography and space experiments, and the perspectives.