Origin of Bright Quantum Emissions with High Debye-Waller factor in Silicon Nitride

TL;DR

This study identifies nitrogen-vacancy related defects in silicon nitride as the origin of bright, polarized quantum emissions with high Debye-Waller factors, advancing integrated quantum photonics.

Contribution

It reveals the microscopic defect structures responsible for bright quantum emissions in silicon nitride using hybrid density functional theory.

Findings

Negatively charged N_SiV_N center exhibits a 2.46 eV ZPL with 33% DW factor.

Pseudo-Jahn-Teller distortion creates defect structures with 1.80 eV ZPL and 41% DW factor.

Defects explain visible quantum emissions, enabling integrated silicon-nitride quantum photonics.

Abstract

Silicon nitride has emerged as a promising photonic platform for integrated single-photon sources, yet the microscopic origin of the recently observed bright quantum emissions remains unclear. Using hybrid density functional theory, we show that the negatively charged N$_\text{Si}$V$_\text{N}$ center (NV$^{-}$) in the C$_{1h}$ configuration exhibits a linearly polarized zero-phonon line (ZPL) at 2.46 eV, with a radiative lifetime of 9.01 ns and a high Debye-Waller (DW) factor of 33%. We further find that the C$_{1h}$ configuration is prone to a pseudo-Jahn-Teller distortion, yielding two symmetrically equivalent defect structures that emit bright, linearly polarized ZPL at 1.80 eV with a lifetime of 10.17 ns and an increased DW factor of 41%. These nitrogen-vacancy-related defects explain the origins of visible quantum emissions, paving the way for deterministic and monolithically integrated silicon-nitride quantum photonics.