Modeling and simulation of an insulated-gate HEMT using p-SnO2 gate for high VTH design

Abstract

In this paper, we proposed a novel recess-free insulated-gate High Electron Mobility Transistor (HEMT) with p-SnO2 gate realizing high threshold voltage (VTH) over 2 V. p-SnO2 is used as the gate material instead of traditional Ni/Au gate. Owing to the high work function of the p-SnO2 (both wide bandgap and large electron affinity (χ)), the 2DEG channel under the gate region can be deeply depleted realizing high VTH even with thick AlGaN barrier over 10 nm, which also ensures high channel mobility. An analytical model is presented and verified by experimentally calibrated TCAD simulation. Results show that for a 25 nm Al2O3, VTH of the proposed HEMT reaches 3.1 V with p-SnO2 doping NA = 5 × 1019 cm−3, which is ∼2.5 V higher than that of a conventional MIS-HEMT with the same parameters. Moreover, the specific on-resistance (Ron,sp) of the proposed HEMT is only 1.31 mΩ cm2, which is reduced by 54.8% compared with that of a recessed-gate MIS-HEMT with the same VTH of ∼2.2 V.