P-Channel MOSFETs on Phosphorous-Doped n-Type Diamond

P-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) have been demonstrated on phosphorus-doped n-type diamond epilayers. The p-channel nature arises from the surface conductivity resulting from hydrogenated termination on the n-type diamond surface. The MOSFET exhibits normally-on properties and shows a threshold of 1.8 V for the phosphorus concentration of 1016 cm−3 and an on/off ratio of 107. The maximum drain current is approximately −4.5 mA/mm and the transconductance is 0.75 mS/mm, which decreases as the phosphorus concentration in the n-type diamond epilayer increases. The demonstration of p-channel MOSFETs on n-type diamond epilayers paves the way for the development of complementary MOS (CMOS) circuits on a single diamond wafer.