Novel carbon-doped p-channel GaAs MESFET grown by MOMBE

Abstract

Abstract A high performance GaAs p-MESFET, using carbon as the p-dopant, is demonstrated for the first time. The channel and contact layers were grown by metal organic molecular beam epitaxy (MOMBE). The cap contact layer was highly doped with carbon ( 5 × 10 20 cm −3 ) in order to minimize the parasitic resistance in the field effect transistor (FET) structure. The sheet resistivity and transfer resistance of the contacts were 220 Ω ◊ −1 and 0.2 Ω mm respectively. These are comparable with values achieved on n-type GaAs. The mobility for the carbon-doped channel layer was 110 cm2 V s−1. The room temperature extrinsic transconductance and K-factor values were 50 mS mm−1 and 165 mS V−1 mm with 1 μm gate length and 3.5 μm source-to-drain spacings. The output resistance of the I–V characteristics was around 500 Ω mm. These are the highest room temperature values ever demonstrated for a p-GaAs metal-semiconductor field effect transistor (MESFET).