Epitaxy

Chemistry

Materials science

Optoelectronics

Biochemistry

Electronic structure

Physics

Heterojunction

Valence band

Nanotechnology

Schottky barrier

Catalysis

Ultraviolet

Ultraviolet photoelectron spectroscopy

Band gap

Diode

Semiconductor

Condensed matter physics

Layer (electronics)

Band offset

Non-blocking I/O

ACS Applied Electronic Materials

Ga2O3 is emerging as an interesting semiconductor for high-power electronics and solar-blind ultraviolet photodetectors because of its ultrawide bandgap and high breakdown field. To fully extend its applications in optoelectronics, it is highly desirable to fabricate a p–n heterojunction. In this work, we report detailed investigations on the epitaxial growth and interface properties of a p–n heterojunction consisting of wide bandgap NiO and β-phase Ga2O3. We show that the NiO(111) layer can be grown on β-Ga2O3(201) thin films, with an epitaxial relationship of NiO(111)||β-Ga2O3(201) and NiO{110}||β-Ga2O3(132). The p–n diode exhibits a large current rectification ratio of about 6 orders of magnitude at ±2.0 V. A detailed X-ray photoemission spectroscopy study reveals a "staggered" band alignment with valence band offsets of 2.1 eV. More interestingly, a large upward built-in potential of 1.1 eV for β-Ga2O3 is observed near the interface region. The valence band offset and large built-in potential formed at the heterointerface provide advantageous energetics for the separation and migration of photogenerated excitons, of particular interest for self-powered solar-blind ultraviolet photodetection.

Fabrication and Interfacial Electronic Structure of Wide Bandgap NiO and Ga<sub>2</sub>O<sub>3</sub> p–n Heterojunction

Fabrication and Interfacial Electronic Structure of Wide Bandgap NiO and Ga2O3 p–n Heterojunction

Fabrication and Interfacial Electronic Structure of Wide Bandgap NiO and Ga₂O₃ p–n Heterojunction