A method for forming a semiconductor device comprises forming an insulator layer on a semiconductor substrate, removing portions of the insulator layer to form a first cavity and a second cavity, the first cavity exposing a first portion of the semiconductor substrate an the second cavity exposing a second portion of the semiconductor substrate, growing a first semiconductor material in the first cavity and the second cavity. Growing a second semiconductor material on the first semiconductor material in the first cavity and the second cavity, growing a third semiconductor material on the second semiconductor material in the first cavity and the second cavity. Forming a mask over the third semiconductor material in the first cavity, removing the third semiconductor material from the second cavity to expose the second semiconductor material in the second cavity, and growing a fourth semiconductor material on the second semiconductor material in the second cavity.