Silicon photonic crystal cavities at near band-edge wavelengths

We demonstrate photonic crystal L3 cavities with a resonant wavelength of around 1.078 μm on an undoped silicon-on-insulator, designed to enhance spontaneous emission from phosphorus donor-bound excitons. We have optimised a fabrication recipe using readily available process materials such as polymethyl methacrylate as a soft electron-beam mask and a Chemical Vapour Deposition grown oxide layer as a hard mask. Our bilayer resist technique efficiently produces photonic crystal cavities with a quality factor (Q) of ∼5000 at a wavelength of 1.078 μm, measured using cavity reflection measurements at room temperature. We observe a decrease in Q as the cavity resonance shifts to shorter wavelengths ( Q ≲ 3000 at wavelengths