Leveraging defect-induced internal gain for high-performance β-Ga₂O₃ photodetectors on patterned sapphire substrates

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• Deep-ultraviolet (DUV) photodetectors are crucial for applications requiring solar-blind detection.
• Gallium oxide (Ga₂O₃) is a promising material for DUV optoelectronics due to its wide bandgap.
• Optimizing growth methods is key to enhancing Ga₂O₃-based device performance.

Purpose of the Study:

• To develop a DUV metal-semiconductor-metal (MSM) photodetector using β-Ga₂O₃ thin films.
• To investigate the effect of patterned sapphire substrates (PSS) on β-Ga₂O₃ film growth and device characteristics.
• To achieve high responsivity and detectivity in solar-blind photodetectors.

Main Methods:

• Chemical vapor deposition (CVD) of β-Ga₂O₃ films on patterned sapphire substrates (PSS) and flat sapphire.
• Fabrication of metal-semiconductor-metal (MSM) photodetectors.
• Characterization of film properties, including crystal orientation and defect density.
• Performance evaluation of photodetectors, including responsivity, detectivity, and UV/visible rejection ratio.

Main Results:

• Achieved the first β-Ga₂O₃ films with preferred (510) orientation on PSS.
• The film on PSS showed high defect densities, leading to exceptional responsivity (106.5 A/W) and detectivity (1.36 × 10¹³ Jones).
• Demonstrated a UV/visible rejection ratio exceeding 10⁴, confirming solar-blind operation.
• Identified the impact of defects on dark current and response time.

Conclusions:

• Defect engineering in β-Ga₂O₃ grown on PSS is a viable strategy for high-performance DUV photodetectors.
• The growth mechanism on PSS offers insights for scalable and cost-effective device fabrication.
• β-Ga₂O₃ on PSS shows significant potential for advanced solar-blind photodetector applications.