A method of forming a fin field effect transistor (finFET) device includes forming a silicon fin on a substrate; forming an inner spacer adjacent to a first portion of the silicon fin; forming silicon germanium regions adjacent to a second portion of the silicon fin and the inner spacer; and oxidizing the silicon germanium regions, such that the second portion of the silicon fin that is located adjacent to the silicon germanium regions is converted to a silicon germanium channel region during oxidizing of the silicon germanium regions, and such that the first portion of the silicon fin is protected by the inner spacer during oxidation of the silicon germanium regions, wherein the first portion of the silicon fin comprises a silicon buffer region located between the silicon germanium channel region and a source/drain region of the finFET device.