A semiconductor device includes a channel region; a gate dielectric over the channel region; and a gate electrode over the gate dielectric. A first source/drain region is adjacent the gate dielectric, wherein the first source/drain region is a semiconductor region and of a first conductivity type. A second source/drain region is on an opposite side of the channel region than the first source/drain region, wherein the second source/drain region is a metal region. A pocket region of a second conductivity type opposite the first conductivity type is horizontally between the channel region and the second source/drain region.