Enhancement of bulk second-harmonic generation from silicon nitride films by material composition

TL;DR

This study demonstrates a significant enhancement in second-harmonic generation efficiency in silicon nitride films by adjusting material composition, achieving high susceptibility and low optical losses suitable for photonic applications.

Contribution

It provides a detailed tensorial analysis of SHG in silicon nitride films with varying compositions, revealing controllable nonlinear optical properties through fabrication parameters.

Findings

Six-fold increase in second-order susceptibility from least to most silicon-rich samples

Maximum susceptibility of approximately 5 pm/V in silicon-rich films

Optical losses remain below 6 dB/cm, suitable for practical use

Abstract

We present a comprehensive tensorial characterization of second-harmonic generation from silicon nitride films with varying composition. The samples were fabricated using plasma-enhanced chemical vapor deposition, and the material composition was varied by the reactive gas mixture in the process. We found a six-fold enhancement between the lowest and highest second-order susceptibility, with the highest value of approximately 5 pm/V from the most silicon-rich sample. Moreover, the optical losses were found to be sufficiently small (below 6 dB/cm) for applications. The tensorial results show that all samples retain in-plane isotropy independent of silicon content, highlighting the controllability of the fabrication process.