Evaluation of diode characteristics for fully vertical β-Ga₂O₃ on silicon (100) substrate

In this article, β-Ga₂O₃ film was deposited on the p-Si (100) substrate using pulsed laser deposition (PLD) technique for rapidly emerging Ga₂O₃-based Schottky barrier diodes (SBDs). Although X-ray diffraction (XRD) result reveals a polycrystalline trending film, a smooth and uniform as-grown surface has been characterized by atomic force microscope (AFM) and field-emission scanning electron microscope (FESEM). Further, we have investigated metal–semiconductor (M–S) contact behavior of the fully vertical SBDs with the four different metals such as aluminum (Al), silver (Ag), gold (Au), and platinum (Pt) on Ga₂O₃ after forming ohmic contacts on the backside of the Si substrate. The barrier heights of all four metals are typically in the range of 0.51–0.69 eV and 0.72–1.41 eV as obtained from the current–voltage (I–V) and capacitance–voltage (C–V) characteristics, respectively. The carrier concentration is ~ 10¹⁶ cm⁻³ as calculated using C–V characteristics. The power device indices, namely breakdown voltage (V_BR) of 19, 26, 90, and 99 V and the on-state resistance (R_ON) values ~ 19.82, 149.19, 7.45 and 156.25 Ω cm² are also obtained for the Al/Ga₂O₃, Ag/Ga₂O₃, Au/Ga₂O₃, and Pt/Ga₂O₃ diodes, respectively. The Baliga Figure of Merits (V²_BR/R_ON) for the Au/Ga₂O₃ diode is found out to be the highest (90.73 W cm⁻²). As the SBDs are fabricated on n-Ga₂O₃/p-Si heterojunction, it is expected to have two back-to-back diodes in the device structure. However, non-existence of back-to-back diodes has been confirmed by temperature dependence I–V characteristics due to possible Poole–Frenkel (P–F) tunneling at the Ga₂O₃/Si heterojunction.