Delta-Doping Effect on the Performance of β-Ga2O3 MOSFETs with Different Gate Dielectric Layers

Depletion-mode β-Ga2O3 MOSFETs can provide highly conductive channels, while further enhancement of channel carrier concentration and gate electrostatic control remains important for improving current-driving capability and reducing on-state resistance. In this work, the effects of delta-layer engineering and gate dielectric optimization on the electrical performance of β-Ga2O3 MOSFETs were systematically investigated. An ultrathin N+-Ga2O3 delta-doped layer (2 × 1012 cm–2) was introduced between the N–-Ga2O3 channel and the (Al0.21Ga0.79)2O3 barrier layer to enhance carrier concentration, while Al2O3, HfO2, and Al2O3/HfON/HZO gate dielectrics were employed to improve gate control. Compared with the undoped Al2O3 device, delta doping increased the ON-state current from 1.46 to 3.95 mA/mm and reduced the ON-resistance from 10.26 to 5.46 kΩ·mm. Further dielectric engineering yielded a maximum ON-state current of 7.55 mA/mm, an ON/OFF current ratio of 9.33 × 106, and a minimum ON-resistance of 2.34 kΩ·mm. Although enhanced ON-state drain current was achieved, the breakdown voltage decreased from 850 to 641 V, highlighting the trade-off between current-driving capability and breakdown voltage. These findings demonstrate that channel carrier engineering through delta doping, together with appropriate gate-dielectric engineering, provides an effective strategy for improving the performance of β-Ga2O3 power MOSFETs.