Carbide contacts on homoepitaxial diamond films

摘要

We present experimental investigations of the structural and electrical properties of carbide contacts on homo-epitaxial p-type diamond films in order to achieve Schottky diodes working at high temperatures with highly adhesive ohmic and Schottkycontacts on diamond. For ohmic contacts, the reaction of molybdenum deposited by magnetron sputtering on homo-epitaxial diamond layer is studied through X-ray diffraction and Rutherford backscattering. The formation of hexagonalα-Mo{sub}2C begins at700250L? However, the residual oxygen is exo-diffused only at 900℃ and for undoped diamond. Nevertheless, ohmic contacts are achieved after annealing at 900℃, with a low contact resistivity at a boron concentration of 1.6× 10{sup}21 cm{sup}-3. ForSchottky contacts the in-situ reaction under ultra-high vacuum between Er and a non-oxidized diamond surface begins at 700℃. A potential barrier height of 1.9 eV and a rectification ratio larger than 10{sup}3 at 4 V at least up to 500℃ are obtained. ineach case, coating layers intended to protect carbides against oxidation are assessed.