This dissertation embarks on a comprehensive exploration of electric field management strategies and dielectric engineering techniques tailored to overcome intrinsic challenges in β-Ga2O3 power devices, particularly focusing on high-voltage applications where wide- and ultra-wide-bandgap semiconductors have a distinct edge over silicon. With the introduction of wide-bandgap materials such as SiC and GaN, and now ultra-wide-bandgap β-Ga2O3, there exists an opportunity to achieve unprecedented efficiencies in power electronics, thanks to these materials’ higher breakdown fields and better thermal stability. However, to fully harness the potential of β -Ga2O3, this dissertation addresses the unique challenges that arise from its lack of viable p-type doping. By proposing novel dielectric-assisted design methodologies, this work makes significant strides in establishing β -Ga2O3 as a viable solution for future high-power, high-voltage applications.

In the first section, the focus is on β -Ga2O3 Schottky barrier diodes (SBDs) and the development of advanced field management strategies using high-permittivity (κ) dielectric materials. High-permittivity dielectrics are introduced as field plate oxides to mitigate edge field crowding and to control the electric field at the metal/semiconductor interface. This design enables the SBDs to achieve a power figure of merit (FOM) of 1.34 GW/cm2, demonstrating the efficacy of high-κ dielectric-assisted RESURF (reduced surface field) designs for managing leakage currents—an essential consideration for devices operating in the kilovolt regime. By creating a trench SBD structure that integrates both high- and low-work-function anode contacts, significant reductions in leakage current and improved breakdown voltages are achieved. The low work-function anode contact, in particular, demonstrates a breakdown voltage exceeding 3 kV while maintaining a low turn-on voltage of just 0.5 V, which positions it as a promising candidate for high-power applications, rivaling and, in certain parameters, surpassing commercial bare-die SiC SBDs.

The work further pioneers the concept of a dielectric superjunction, which emulates the charge-balancing benefits of a traditional p/n superjunction without the requirement for p-type doping and associated stringent charge balance. By leveraging high-κ dielectric materials, a lateral dielectric superjunction device is realized with a figure of merit of 1.47 GW/cm2 along with a higher doped channel (ND = 3 × 10^17 cm^−3) for lowered on-resistance, showcasing the potential of this dielectric-based approach to circumvent the intrinsic limitations of β-Ga2O3. The dielectric superjunction structure also simplifies the design process by eliminating the need for precise charge balancing, a common and challenging constraint in traditional superjunction structures. This proof-of-concept device opens pathways for scaling up and further refining superjunction devices for vertical implementations in high-power electronics.

In the latter half, the dissertation transitions to address the pressing need for advanced β-Ga2O3 vertical transistor architectures, where conventional lateral designs fall short due to limited current handling capability and surface field-handling issues. A key contribution here is the development of an in-situ dielectric deposition technique using Metal-Organic Chemical Vapor Deposition (MOCVD) that enables pristine, low-defect density dielectric/semiconductor inter-faces. This interface quality is critical for the reliable performance of gate dielectrics in power transistors, as impurities or defects at the interface can significantly impact device stability and operation under high electric fields. Detailed characterization of the dielectric properties and interface quality is conducted, revealing the improvements in breakdown voltage and reliability made possible through precise deposition conditions. The high-temperature MOCVD process also enhances the dielectric layer’s density and crystallinity, further contributing to its breakdown robustness. By adjusting deposition conditions, the dielectric’s lifetime and stability are optimized, establishing a foundation for the deployment of these dielectrics in high-power β-Ga2O3 transistors.

The culmination of this work is the demonstration of a normally-off vertical β-Ga2O3 fin transistor, achieving a breakdown voltage over 1 kV, which represents a significant advancement toward viable power transistors in this material. This device, designed without the need for p-type doping, leverages geometric design techniques to effectively manage electric fieldsand provide enhancement mode operation. Further refinements to edge termination and alternative transistor structures are explored, with capacitance measurements verifying their improved switching performance. This study underscores the importance of novel transistor designs in pushing the boundaries of β-Ga2O3 technology, particularly for high-voltage applications where traditional device designs cannot accommodate the material’s limitations.

In conclusion, this dissertation offers an innovative perspective on β -Ga2O3 device engineering, demonstrating that while p-type doping is advantageous in wide-bandgap devices, it is not a necessity for high-performance β -Ga2O3 power electronics. Instead, high-κ dielectric materials emerge as a promising alternative for electric field management, mitigating leakage currents and optimizing breakdown performance without the complexities associated with p-type doping. Through the use of high-κ dielectric materials and alternative electric field management techniques, the intrinsic challenges of β-Ga2O3 are addressed, showcasing the material’s potential as a disruptive technology in power electronics.