Modeling of Non-Ideal Ni/Ga2O3 Schottky Contacts by Two-Barrier Thermionic Emission Model

Nickel (Ni) Schottky diodes fabricated on β -Ga2O3 were investigated over a wide temperature range (−50 ◦C to 200 ◦C), revealing a forward bias conduction ruled by a nonideal thermionic emission (TE) model. Larger area diodes were found to deviate from ideal TE behavior, especially at lower measurement temperatures. Two different diode families were investigated. The experimental current–voltage ( I – V ) characteristics were modeled using a parallel-diode configuration, allowing the extraction of a larger barrier height ( ΦB1 ) of about 1.43 or 1.48 eV, associated with the main diode area, and a smaller barrier height ( ΦB2 ) of about 1.04 or 1.07 eV, corresponding to a small defective fraction of the contact area. In both cases, a difference of approximately 0.4 eV was observed between ΦB1 and ΦB2 . This result suggests that in both diode families, the presence of Φ B2 can be correlated to the same type of defects, but with different spatial extension within the diode.