Abstract

The κ-phase gallium oxide (κ-Ga2O3) has emerged as a promising material for next-generation electronic devices owing to its ultra-wide band gap, remarkable spontaneous polarization and unique ferroelectricity. We have investigated the two-dimensional electron gas (2DEG) characteristics and device performance of κ-Ga2O3/GaN HEMTs via numerical simulations. The κ-Ga2O3/GaN heterostructure exhibits a significantly enhanced 2DEG density (~1.05 × 1014 cm−2), which is nearly an order of magnitude higher than that of conventional AlGaN/GaN HEMTs, due to the strong polarization effect. For a barrier thickness of 25 nm, the κ-Ga2O3/GaN HEMT exhibits a maximum drain current density (ID,max) of 4.40 A/mm at VGS = 2 V and a peak transconductance (gm,max) of 0.45 S/mm, accompanied by a steep subthreshold swing (SS) of 63.2 mV/decade. Furthermore, we find that the absolute value of threshold voltage increases with the barrier thickness and the peak transconductance decreases with the increase in barrier thickness. When the thickness reaches 40 nm, the 2DEG density becomes saturated with a value of 1.12 × 1014 cm−2. Moreover, by incorporating a p-type GaN cap layer into the κ-Ga2O3/GaN heterostructure, a normally off operation is achieved, with a positive threshold voltage as the acceptor concentration exceeds 8.0 × 1017 cm−3. These results highlight the potential of κ-Ga2O3/GaN heterostructures for high-performance power electronic applications.

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