Diamond Junction Field-Effect Transistors with Selectively Grown n$^{+}$-Side Gates

Abstract

Diamond junction field-effect transistors (JFETs) were fabricated by the selective growth of phosphorus-doped n+-type diamond. The n+ diamonds were grown at the sidewalls of a boron-doped p-type channel, and lateral pn junctions were formed under optimized conditions of microwave plasma chemical vapor deposition. We confirmed that the drain current could be well modulated by controlling the depletion layers in the p-channel, and the devices turned into the off-current state when the channel was closed by the depletion layers. JFETs showed a very low leakage current in the 10-15 A regime, high on/off ratios of 107–108, and steep subthreshold swings of 95–120 mV/decade.