Design and Analysis of High-Performance Schottky Barrier β-Ga2O3 MOSFET With Enhanced Drain Current, Breakdown Voltage, and PFOM

Abstract

In this article, a Schottky barrier β-Ga₂O₃ MOSFET is proposed. It shows improvements in drain saturation current, I_on/I_off ratio, transconductance, and off-state breakdown voltage. The proposed design, which implements the Schottky barrier source and drain contacts, has led to reduced on-state resistance (R_on), reduced forward voltage drops, faster switching speed, higher frequency, and improved efficiency. After device optimization, we determined that a source and drain having a work function of 3.90 eV result in the highest drain saturation current of (I_ds) 264 mA. Additionally, in the transfer characteristics, we demonstrate that increasing the channel doping concentration led to a shift toward depletion mode operation, while decreasing the doping concentration moved the device toward enhancement mode at the cost of drain current. Analysis of lattice temperature and self-heating effects on different substrates has also been performed. Furthermore, introducing a passivation layer of SiO₂ as a gate oxide and an unintentionally doped (UID) layer of 400 nm doping concentration of 1.5 × 10¹⁵ cm⁻³, results in further significant improvements in the drain saturation current (I_ds) of 624 mA and transconductance of 38.09 mS, approximately doubling their values compared with the device without a passivation layer of SiO₂ and an I_on/I_off ratio of 10¹⁵, and the device's performance at various substrate temperatures has been evaluated. In addition, the inclusion of a passivation layer of SiO₂ improves the breakdown voltage to 2385 V, which is significantly high compared with the conventional device. Moreover, the lower specific-on-resistance R_on,sp of 7.6 mΩ/cm² and higher breakdown voltage then the high-power figure of merit (PFOM) (BV²/R_on,sp) of 748 MW/cm² have been achieved.