Depletion-mode InGaAs metal-oxide-semiconductor field-effect transistor with oxide gate dielectric grown by atomic-layer deposition

摘要

Recently, significant progress has been made on GaAs metal-oxide-semiconductor field-effect transistors (MOSFETs) using atomic-layer deposition (ALD)-grown A1_2O_3 as gate dielectric. We show here that further improvement can be achieved by inserting a thin In_(0.2)Ga_(0.8)As layer as part of the channel between Al_2O_3 and GaAs channel. A 1-μm-gate-length, depletion-mode, n-channel In_(0.2)Ga_(0.8)As/GaAs MOSFET with an Al_2O_3 gate oxide of 160 A shows a gate leakage current density less than 10~(-4) A/cm~2, a maximum transconductance ～ 105 mS/mm, and a strong accumulation current at V_(gs) > 0 in addition to buried-channel conduction. Together with longer gate-length devices, we deduce electron accumulation surface mobility for In_(0.2)Ga_(0.8)As as high as 660 cn~2/V s at A1_2O_3 /In_(0.2)Ga_(0.8)As interface.