In situ heteroepitaxial construction and transport properties of lattice-matched α-Ir2O3/α-Ga2O3 p-n heterojunction

The construction of Ga2O3-based p-n heterojunction offers an alternative strategy to realize bipolar power devices; however, lattice mismatch usually leads to undesirable device performance and makes interface engineering more challenging. In this work, we demonstrated the construction of lattice-matched p-n heterojunctions by the in situ hetero-epitaxy of p-type α-Ir2O3 on n-type Si-doped α-Ga2O3 using the mist-chemical vapor deposition technique. The α-Ga2O3/α-Ir2O3 p-n heterojunction shows single-crystalline corundum structures and well-defined rectifying characteristics. The transport mechanism has been identified to be space-charge-limited current conduction, which is induced by interfacial traps in an ultrathin disordered layer at the α-Ga2O3/α-Ir2O3 interface. Through thermal treatment in oxygen ambient, interfacial trapping states are suppressed, and more shallow acceptors of Ir vacancies are activated, both of which lead to the profound reduction of reverse leakage current, thus the improved current rectification ratio. The p-type α-Ir2O3 with advantages of lattice matching to α-Ga2O3 provides a promising strategy to realize high-performance bipolar power devices.