Electrical characterisation of silicon pn-junctions terminated with diamond

Properties of the silicon/diamond interface are investigated in terms of leakage current measurements of silicon pn-junction diodes. Two different types of pre-treatment and deposition methods of polycrystalline diamond were investigated, microwave assisted plasma CVD (MPCVD) with bias pre-treatment and hot filament CVD (HFCVD). It was found that when the depletion region was in contact with the silicon/diamond interface the leakage current was increased. Generation at surface states, with a surface recombination velocity of about 9 × 106 cm s−1, was found to be the responsible mechanism in the MPCVD samples, while surface conduction was also contributing to the leakage current in the HFCVD samples. However, near ideal diode characteristics with low leakage current were obtained by introducing a thin silicon dioxide layer between the silicon and diamond.