Formation of Silicon Wires within Optical Fibers Via High-Pressure Chemical Vapor Deposition

High aspect-ratio silicon wire waveguides can be fabricated by high-pressure chemical vapor deposition within microcapillary templates. In this deposition process, a precursor comprised of a mixture of silane and helium flows within a microcapillary template at high pressure. The microcapillary wall is heated to facilitate silane decomposition resulting in silicon film deposition. Although void-free filling of the microcapillary template is desirable to obtain high quality waveguides, complete filling of the plugged central channel over lengths of centimeters is challenging in view of its extreme aspect ratio. Experimental observations show the variation in the thickness of the deposited silicon layer with axial position and time within the microcapillary templates. Numerical simulations of growth dynamics are performed to examine the non-uniformity in the thickness of the deposited semiconductor within the microcappillary.  The growth profile predicted by the numerical simulation is in a good agreement with the experimental measurements of the semiconductor thickness profile.