Influence of Metal-Diamond Interfaces on the Response of UV Photoconductors

A systematic investigation on the influence of metal-diamond interfaces on the electro-optical properties and on the UV response of CVD diamond photo-detectors was carried out in order to identify the optimal electric contacts maximizing the performance. To this purpose, a set of four nearly identical diamond samples has been grown using the microwave plasma enhanced CVD technique. Micro-Raman spectroscopy and photoluminescence have been utilized to assess their quality. Interdigitated planar contacts have been photolithographically deposited on each sample, using different layered metals. In particular, titanium-gold, chromium-gold, aluminum-gold and gold were selected. The performance of these detectors has been investigated under steady photon irradiation in the 120-300-nm wavelength range. The experimental results have been compared and discussed with respect to I-V characteristics, dark current levels, signal-to-noise ratio, spectral response and time response.