A method of forming a semiconductor device includes forming a fin extending from a substrate. The fin has a source/drain (S/D) region and a channel region. The fin includes a first semiconductor layer and a second semiconductor layer on the first semiconductor layer. The first semiconductor layer has a first composition, and the second semiconductor layer has a second composition different from the first composition. The method further includes removing the first semiconductor layer from the S/D region of the fin such that a first portion of the second semiconductor layer in the S/D region is suspended in a space. The method further includes epitaxially growing a third semiconductor layer in the S/D region, the third semiconductor layer wrapping around the first portion of the second semiconductor layer.