Novel ternary approach to create ultra-wide bandgap heterojunctions for power electronics

Since shallow p-type dopants are not available for Ga2O3, bipolar homojunction Ga2O3 devices are not possible, so the vast majority of the reported Ga2O3 devices have employed unipolar device architectures: i.e. Schottky barrier devices or lateral, isotype field-effect transistors (FETs). One potential answer to this limitation is to integrate n-type Ga2O3 with p-type NiO so as to design novel vertical p–n heterojunction devices (e.g. power diodes and/or photodetectors). With a bandgap of 3.7 eV, NiO is the complementary p-type oxide of choice through its’ robustness and flexible dopability. The minority carrier nature of these devices should allow lower on-resistances and, therefore, give better on-state performance and an improved range of functionality. The vertical architecture will also bring reductions in current crowding and a smaller footprint (which directly increases circuit integration density and reduces cost per device). In this work, we report the heteroepitaxy of p-Mg)NiO on n-(Al)Ga2O3 using pulsed laser deposition. This novel ternary approach gives better band matching between the p and n layers than the more conventional binary (p-NiO/n-Ga2O3) architecture.