NIST team grows 2 μm crack-free silicon nitride on sapphire for wide-band photonics
jwt0625 · x · 2026-10-15
arXiv paper 2610.15754 by Zhaohui Ma and 7 co-authors (NIST et al.) develops low-residual-stress stoichiometric silicon nitride on sapphire for wide-band photonics:
- Background: LPCVD silicon nitride on oxidized silicon is the dominant wide-band photonics platform, but 1000 MPa residual tensile stress causes cracking beyond 400 nm — a major fabrication challenge.
- Approach: systematic characterization of LPCVD SiN on sapphire via thin-film stress analysis, ellipsometry and prism-coupling measurements of refractive index and loss, plus swept-wavelength spectroscopy of devices across a broad wavelength range.
- Results: crack-free stoichiometric SiN up to 2 μm thick at only 200 MPa stress; propagation losses of 0.35 dB/cm at 780 nm, 0.37 dB/cm at 1064 nm, and 0.25 dB/cm at 1630 nm; prism-coupling shows film losses below 1 dB/cm down to 500 nm.
Related event: NIST Grows Crack-Free Silicon Nitride on Sapphire(2 posts)→
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