Dopant Molecularization in β-Ga₂O₃: Formation of N₂ under Nonequilibrium Conditions

Area of Science:

• Materials Science
• Solid State Physics
• Oxide Electronics

Background:

• The behavior of dopants in wide-band gap oxides under nonequilibrium conditions is not well understood.
• Understanding dopant behavior is crucial for developing advanced electronic materials.

Purpose of the Study:

• To investigate the microscopic fate of nitrogen dopants in beta-gallium oxide (β-Ga2O3) after implantation.
• To elucidate the local bonding configuration and evolution of nitrogen in β-Ga2O3.

Main Methods:

• Temperature-dependent Nitrogen K-edge X-ray absorption spectroscopy (XAS) was employed.
• First-principles calculations and multiple-scattering simulations were used for spectral analysis.

Main Results:

• XAS spectra revealed a distinct resonance attributed to N≡N (molecular nitrogen) bonding.
• The intensity of the molecular nitrogen signal increased with annealing, indicating its formation.
• Calculations confirmed molecular N2 as the dominant dopant state, forming in defect-rich regions with altered local structures.

Conclusions:

• Implanted nitrogen in β-Ga2O3 primarily forms molecular N2, bypassing substitutional doping.
• Annealing promotes the formation of molecular nitrogen via thermally driven reconfiguration.
• This molecularization pathway offers a mechanism for dopant deactivation in oxides under nonequilibrium conditions.