Si thin films were deposited by low pressure chemical vapor deposition on quartz and oxidized Si substrates at temperatures ranging from 540 to 640-degrees-C. X-ray diffraction (XRD) indicates that films deposited greater-than-or-equal-to 590-degrees-C are increasingly polycrystalline with a [220] orientation, while films deposited less-than-or-equal-to 580-degrees-C are amorphous. After deposition, the Si films were rendered porous (PoSi) by stain-etching in HF:HNO3:H2O. XRD and Raman spectroscopy indicate that initially polycrystalline films retain their crystallinity after becoming porous. Posi films deposited greater-than-or-equal-to 590-degrees-C exhibit visible (approximately 650-670 nm) photoluminescence (PL) at room temperature under UV excitation. Films deposited less-than-or-equal-to 580-degrees-C do not luminesce, even after a very long etch time which produces a significant increase in the surface pore area density The XRD signal of the Si films and the corresponding PL intensity exhibit a qualitatively similar dependence on deposition temperature. A certain degree of crystallinity in the PoSi material appears to be a necessary condition for photoluminescence.