Ohmic contacts for phosphorus-doped n-type diamond

Electric contacts for phosphorus (P)-doped n-type diamond films have been studied. The P-doped {111} homoepitaxial diamond thin films with n-type conduction are grown on high temperature high pressure diamond substrates by microwave-enhanced plasma chemical vapor deposition. The donor density and crystallinity of the phosphorus-doped diamond films were varied depending on the growth conditions. Metals with different work function and different reactivity to diamond films were deposited on the P-doped diamond films as electrodes. Ion implantation was also applied for introducing electrically active defects in diamond films. We found that n-type rectification properties with average Schottky barrier height of 2.4 eV were obtained from both Au and Cu contacts deposited on lightly doped diamond films with donor density N-D of 5 x 10(17) cm(-3). Ohmic properties were obtained from electrodes on heavily doped layer with N-D of over 1 x 10(10) cm(-3) Electrodes formed on the diamond film with electrically active defects also show Ohmic properties. These features indicate that the behavior of contacts formed on P-doped n-type diamond films is similar to those on typical n-type semiconductors.