Horizontal gate-all-around devices and methods of manufacturing are described. The hGAA devices comprise a fully-depleted silicon-on-insulator (FD-SOI) under the channel layers in the same footprint as the hGAA. The buried dielectric insulating layer of the FD-SOI comprises one or more of silicon oxide (SiOx), silicon nitride (SiN), silicon carbide (SiC), and a high-k material, and the buried dielectric insulating layer has a thickness in a range of from 0 nm to 10 nm.