Carbon and Silicon Impurity Defects in GaN: Simulating Single-Photon Emitters by First Principles

Area of Science:

• Materials Science
• Quantum Optics
• Solid-State Physics

Background:

• Defect single-photon emitters (SPE) in gallium nitride (GaN) are attractive for room-temperature operation, narrow linewidths, and high brightness.
• The exact mechanisms behind SPE in GaN are not fully understood due to numerous potential intrinsic defects.

Purpose of the Study:

• To systematically investigate defect interactions with common dopants (carbon, silicon) in GaN.
• To identify novel, high-speed defect single-photon sources.
• To elucidate the properties of specific ternary defects for photonic applications.

Main Methods:

• Ab initio calculations were performed to study defect formation and properties.
• Density Functional Theory (DFT) using Perdew-Burke-Ernzerhof (PBE) and Heyd-Scuseria-Ernzerhof (HSE) functionals.
• Analysis of defect energy levels, emission wavelengths, and lifetimes.

Main Results:

• A ternary defect, N_GaV_NC_N, was identified as a promising high-speed single-photon source.
• This carbon-related defect exhibits a lifetime < 1 ns and a zero-photon line (ZPL) at 864 nm.
• A silicon-related defect, N_GaV_NSi_N, was found unsuitable due to its energy level within the conduction band.

Conclusions:

• Carbon doping of GaN can create efficient, high-speed single-photon emitters suitable for fiber communication.
• Ternary defects involving intrinsic vacancies and dopants are key to developing advanced photonic devices.
• Further investigation into defect engineering in GaN holds potential for high-performance single-photon sources.