Microstructure Evolution and Electrical Behaviors for High-Performance Cu₂O/Zr-Doped β-Ga₂O₃ Heterojunction Diodes

Area of Science:

• Materials Science
• Semiconductor Physics
• Device Engineering

Background:

• Beta-gallium oxide (β-Ga₂O₃) is an ultrawide band gap semiconductor critical for high-power, high-frequency, and deep-UV optoelectronics.
• Low-temperature fabrication of β-Ga₂O₃ films is desired for flexible electronics but often results in poor crystallinity and defects, limiting device performance.
• High-quality heterojunction interfaces are essential for advanced semiconductor devices.

Purpose of the Study:

• To investigate the effect of Zirconium (Zr) doping on the crystallinity and microstructure of β-Ga₂O₃ films deposited at low temperatures.
• To fabricate and characterize cuprous oxide (Cu₂O)/Zr-doped β-Ga₂O₃ heterojunction diodes.
• To evaluate the electrical performance and interface quality of the fabricated heterojunction diodes.

Main Methods:

• Fabrication of Cu₂O/Zr-doped β-Ga₂O₃ heterojunction diodes using magnetron sputtering without intentional substrate heating.
• Microstructural analysis to assess film crystallinity and phase purity.
• Electrical characterization including current-voltage (J-V) and capacitance-voltage (C-V) measurements.

Main Results:

• Zr doping significantly improved the crystallinity of β-Ga₂O₃ films at low substrate temperatures, transitioning from amorphous to crystalline β phase.
• Crystalline β-Ga₂O₃ promoted epitaxial growth of Cu₂O and suppressed the formation of the detrimental CuO secondary phase at the interface.
• The Cu₂O/Zr-doped β-Ga₂O₃ heterojunction diodes exhibited near-ideal electrical behavior with a low ideality factor of 1.6.

Conclusions:

• Zr doping is an effective strategy to achieve high-quality β-Ga₂O₃ films and heterojunction interfaces at low deposition temperatures.
• The developed fabrication method enables low-temperature production of high-performance β-Ga₂O₃-based heterojunction devices.
• This approach holds promise for applications in flexible electronics and other advanced electronic and optoelectronic devices.