Study on Metal-Oxide Field Effect Transistors of β-Gallium Oxide with AlGaO Spacer Layer Grown on Sapphire for High-Power Device Applications

This study utilized metal–organic chemical vapor deposition technology to grow β-Ga2O3 epitaxial layers on sapphire substrates and fabricate lateral β-Ga2O3 field-effect transistors (FETs). To enhance the performance of these FETs, a β-Ga2O3/(Al0.33Ga0.67)2O3 structure was incorporated. The resulting FETs demonstrated high on-state current (Ion), low on-state resistance (Ron), and a high on–off ratio of drain current, indicating excellent two-dimensional electron gas (2DEG) characteristic offered by β-Ga2O3/(Al0.33Ga0.67)2O3 structure. By optimization of the thickness and doping concentration of β-Ga2O3, high-performance 2DEG β-Ga2O3 FETs were achieved, which satisfied the stringent requirements for power devices. Notably, the heavily doped β-Ga2O3/(Al0.33Ga0.67)2O3 structure led to a significant improvement in performance, with the saturation current (ID,sat) increasing from 0.16 to 11.4 mA/mm, a remarkable 6925% increase, and the breakdown voltage rising from 331 to 687 V, an increase of 107.25%. The relative performance of the device with and without AlGaO was also simulated. These enhancements were primarily due to the effective reduction of leakage current density and 2DEG formation by the β-Ga2O3/(Al0.33Ga0.67)2O3 layer, which was grown by the importance of precise growth parameters and structural design in advancing the performance of β-Ga2O3 FETs, making them highly promising for high-power applications.