Vertical $\beta$ -Ga $_{\text{2}}$ O $_{\text{3}}$ Power Transistors: Fundamentals, Designs, and Opportunities

Beta-gallium oxide ( $\beta$ -Ga $_{\text{2}}$ O $_{\text{3}}$ ) has emerged as a promising semiconductor material for high-voltage, high-temperature, and radiation-resistant electronics, offering performance advantages that surpass those of silicon and other wide bandgap semiconductors. Breakthroughs in the fabrication process and structure designing have led to the rapid development of vertical $\beta$ -Ga $_{\text{2}}$ O $_{\text{3}}$ power transistors and shown their potential superiority for next-generation power devices. In this article, we present a review of major types of vertical $\beta$ -Ga $_{\text{2}}$ O $_{\text{3}}$ transistors including current aperture vertical electron transistors (CAVETs), vertical fin-channel field-effect transistors (FinFETs), vertical diffused barrier field-effect transistors (VDBFETs), and U-shaped trench-gate metal-oxide-semiconductor field-effect transistors (UMOSFETs). We present their operation principles, performance achievements, design evolutions, and detailed optimizations with mechanism research. Comparisons are highlighted to analyze the advantages and inadequacies caused by their unique process approaches and enhancement-mode realizations. In the end, we address challenges and outlooks for the future development of vertical $\beta$ -Ga $_{\text{2}}$ O $_{\text{3}}$ transistors.