Localized UV emitters on the surface of β-Ga₂O₃

Area of Science:

• Materials Science
• Solid-State Physics
• Optoelectronics

Background:

• Monoclinic gallium oxide (β-Ga₂O₃) is an ultra-wide bandgap semiconductor with potential for power electronics.
• Weak band-edge luminescence due to self-trapped holes has limited its use in light-emitting applications.
• Previous research has not considered β-Ga₂O₃ a promising material for light emission.

Purpose of the Study:

• To investigate the luminescence properties of β-Ga₂O₃ beyond its band-edge emission.
• To identify the source of near-UV luminescence in β-Ga₂O₃.
• To assess the potential of β-Ga₂O₃ for UV optoelectronic devices.

Main Methods:

• Optical imaging techniques were employed to study luminescence.
• Structural imaging methods were used to correlate defects with emission.
• Photoluminescence (PL) spectroscopy was performed to characterize emission properties.

Main Results:

• Localized surface defects in β-Ga₂O₃ were identified.
• These defects exhibit bright near-UV emission (3.27 eV, 380 nm) upon sub-bandgap light excitation.
• The PL emission intensity from these defects is significantly higher (50x) than that of ZnO.

Conclusions:

• Localized surface defects are responsible for the bright near-UV emission in β-Ga₂O₃.
• This finding contradicts the previous understanding of β-Ga₂O₃'s luminescence limitations.
• β-Ga₂O₃ is a promising candidate for UV optoelectronic applications due to defect-related emission.