Embodiments of the invention include a semiconductor device having a fin-shaped channel with a bottom surface, sidewalls and a top surface. A first source or drain (S/D) region is communicatively coupled to the fin-shaped channel, and a sub-channel region is between the bottom surface of the fin-shaped channel and a substrate. A U-shaped dielectric region within a first portion of the sub-channel region, wherein the U-shaped dielectric region includes a bottom isolation layer and a first inner spacer region. A wrap-around gate structure extends around the bottom surface, the sidewalls and the top surface of the fin-shaped channel, wherein a bottom region of the wrap-around gate structure is within a second portion of the sub-channel region.