Hot-wire polysilicon waveguides with low deposition temperature

We fabricated and measured the optical loss of polysilicon waveguides deposited using Hot-Wire Chemical Vapour Deposition (HWCVD) at a temperature of 240°C. A polysilicon film 220 nm thick was deposited on top of a 2000 nm thick PECVD silicon dioxide. The crystalline volume fraction of the polysilicon film was measured by Raman spectroscopy to be 91%. The optical propagation losses of 400, 500, and 600 nm waveguides were measured to be 16.9, 15.9, and 13.5 dB/cm, respectively, for transverse electric (TE) mode at the wavelength of 1550 nm. Scattering loss is expected to be the major contributor to the propagation loss