The present disclosure provides embodiments of semiconductor devices. A semiconductor device according to the present disclosure include an elongated semiconductor member surrounded by an isolation feature and extending lengthwise along a first direction, a first source/drain feature and a second source/drain feature over a top surface of the elongated semiconductor member, a vertical stack of channel members each extending lengthwise between the first source/drain feature and the second source/drain feature along the first direction, a gate structure wrapping around each of the channel members, an epitaxial layer deposited on the bottom surface of the elongated semiconductor member, a silicide layer disposed on the epitaxial layer, and a conductive layer disposed on the silicide layer.