β-Ga2O3 is emerging as a popular wide bandgap semiconductor material due to its large breakdown field of 6-8 MV/cm, electron mobility up to 300 cm2/V-s, and readily available high-quality substrates. However, to realize the true potential of this material, it is important to achieve large electric fields close to the intrinsic breakdown field. The lack of native p-type dopants makes this a challenging task. One way to overcome this challenge is by using large barrier height Schottky barrier diodes. In this work, we demonstrate a very high surface electric field of 4.3 MV/cm in vertical Schottky barrier diodes (SBDs) using sputtered PtOx contacts. Sputtering is a fast technique for depositing metal oxide contacts, but the high energy of incident particles can create defects that lead to pinning of the Fermi level. As an alternative, a technique for fabricating high-quality large barrier height SBDs using molecular beam epitaxy (MBE) grown noble metal oxide contacts on β-Ga2O3, has been demonstrated. The barrier heights for MBE grown metal oxide SBDs showed much better uniformity than sputtered SBDs, further validating the potential of this technique for fabricating uniform reverse blocking junctions.