ISSUES IN DIAMOND DEVICE FABRICATION

We have been investigating two key aspects of diamond device technology, with the goal of fabricating active electronic devices. We have developed an ohmic contact metallization with a specific contact resistivity of 2 × 10-5 Ω-cm2 on heavily doped diamond films. Ion implantation studies indicate that boron implanted at a substrate temperature of 80 K with a multiple implant scheme (25 keV, 1.5 × 1014 B+/cm2; 50 keV, 2.1 × 1014 B+/cm2; and 100 keV, 3.0 × 1014 B+/cm2), and annealed at 1273 K in nitrogen can be electrically activated, resulting in a p-type conducting layer 210 nm thick. Van der Pauw resistivity and Hall effect measurements as a function of temperature indicated a room temperature carrier concentration of 5 × 1015/cm3, carrier mobility of 30 cm2/V-s. Preliminary testing of an insulated gate field effect transistor fabricated in this layer has been carried out. Current saturation over a wide range of gate voltages and pinch-off at a gate bias of 12 V have been observed, with a measured transconductance of 3.9 μS/mm. © 1992.