A method includes forming at least one fin on a semiconductor substrate. A silicon alloy material is formed on the fin and on exposed surface portions of the substrate. A thermal process is performed to define a silicon alloy fin from the silicon alloy material and the fin and to define silicon alloy surface portions from the silicon alloy material and the exposed surface portions of the substrate. A semiconductor device includes a substrate, a fin defined on the substrate, the fin comprising a silicon alloy and having a substantially vertical sidewall, and silicon alloy surface portions on the substrate adjacent the fin.