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Beta-Gallium Oxide (β-Ga2O3) is an ultra-wide bandgap semiconductor with a 4.8 eV bandgap, presenting a promising material platform for enhanced power-switching applications. The potential is underlined by its high breakdown field strength of approximately 8 MV/cm and the availability of bulk substrates that can be grown from melt-based methods. The elevated breakdown field strength shows superior theoretical power figure of merit compared to established Si, SiC, and GaN technologies. This dissertation delves into the crucial aspects of realizing state-of-the-art β-Ga2O3 vertical power devices. In Chapter 1, the motivation behind this work is discussed, emphasizing the significance of vertical Ga2O3 device technology. The development of vertical Ga2O3 power devices pose considerable challenges, particularly due to the unavailability of p-type doping. To address this, vertical trench architecture emerges as a viable solution which does not require p-type doping in the active region. However, vertical trench structures introduce their own set of challenges, notably the requirement for a dielectric with a breakdown strength comparable to that of Ga2O3, conventional etching techniques which induce damage to Ga2O3 structures, and effective field termination without p-type doping.Due to the lack of p-type doping a Ga2O3 Schottky barrier diode can be used to make power rectifiers. The breakdown of such a Ga2O3 Schottky barrier is constrained by the high electric field at the Schottky junction. The electrons can tunnel through the narrow triangular potential barrier, resulting in premature breakdown. The use of Ga2O3 heterojunction can reduce such tunneling and improve the surface electric field in Ga2O3 power devices. In this study, by utilizing BaTiO3/Ga2O3 heterojunctions the tunneling barrier was increased. This helped to sustain a higher breakdown field in Ga2O3.Similarly, (AlxGa1-x)2O3/Ga2O3 heterojunction was used to improve the surface electric field. The metal/(AlxGa1-x)2O3 junction has a higher Schottky barrier compared to the metal/Ga2O3 junction. This increased the width of the electron tunneling barrier under reverse bias and helped to sustain a higher electric field in Ga2O3. Another way to achieve high electric field in Ga2O3 vertical devices is the use of trench architecture where the device can be engineered to push the electric field away from the Schottky junction. The first step to realize trench Schottky barrier diodes involves integration with an appropriate dielectric. Al2O3 with a comparable breakdown strength of Ga2O3 can be used for this purpose. At three different temperatures Al2O3 was deposited on Ga2O3. The higher deposition temperatures of Al2O3 helped to support a higher reverse electric field in Ga2O3, exceeding 5.3 MV/cm. The higher deposition temperature also resulted in the crystallinity of the film, which was observed through transmission electron microscopy. This crystallinity affected the forward breakdown characteristics of the dielectric as the nano-crystal grain boundaries facilitated higher leakage current. Further trench Schottky barrier diode was demonstrated using the above mentioned Al2O3 and Ga-atomic beam etching of Ga2O3. The diodes were fabricated along [100] and [010] orientations on a (001) Ga2O3 epitaxial layer. In both orientations, the devices exhibited similar turn-on voltage and on-resistance. In reverse bias, the trench Schottky barrier diodes experienced hard breakdown at 1.4 kV, sustaining a 5.1 MV/cm electric field in Ga2O3. The 2-dimensional electric field distribution of the device was analyzed to understand the breakdown, revealing that the breakdown occurred at the anode edge and was limited by field termination.Next, two field termination techniques for vertical Ga2O3 devices were explored. The first involves a BaTiO3/HfO2 hybrid dielectric stack for field plating, where the field plated devices exhibited breakdown of over 1 kV. This hybrid dielectric stack prevented the conduction through the BaTiO3 in forward bias and helped to sustain the electric field at the anode edge in reverse bias. Another solution involves mesa etching at the anode edge. This significantly reduced the available charge to image at the anode corner, leading to an 80% junction termination efficiency in planar Schottky barrier diodes and can further be implemented on the trench Schottky barrier diodes.The BCl3/Cl2-based etching damage in β-Ga2O3 structures was studied, revealing that the (010) plane tends to experience more damage during etching. This damage resulted in charge compensation and higher on-resistance in Ga2O3 devices. The compensated charge was recovered by annealing the samples above 750°C under ultra-high vacuum. This led to current recovery and reduction in the on-resistance in etched Ga2O3 devices. Using this current recovery method, multi-fin trench SBDs were demonstrated where fins were etched by ICP/RIE using BCl3/Cl2 plasma and current recovery was achieved through annealing at 850°C under ultra-high vacuum. The devices with fins along [100] and [010] directions showed similar on-resistances and turn-on voltages. Under reverse bias, the breakdown occurred at 1.85 kV, and the device sustained an electric field of over 3.2 MV/cm in Ga2O3.In conclusion the future scope of this research is discussed. By understanding the design and the process challenges in realizing vertical trench Schottky barrier diodes, the fabrication steps for trench MOSFET are demonstrated. Using the insights gained from this research, a 5 kV trench diode and transistor are further proposed. Incorporating damagefree trench structures, high-quality dielectric, and efficient field terminations, kV-class Ga2O3 vertical power devices with near-theoretical breakdown fields can be achieved in the future.