The optical and structural properties of sub-micrometer scale Si/SiGe wires grown by solid source molecular beam epitaxy on Si (001) substrates are presented. The structures were grown selectively using SiO2 and Si3N4/SiO2 masks, and have been studied by photoluminescence and high-resolution X-ray diffraction. All samples exhibited a photoluminescence signal from SiGe, but the most intense and narrowest photoluminescence peak (comparable to the Si substrate) was observed from Si/SiGe wires grown in deep-etched Si trenches.