The present disclosure relates to a thermally enhanced semiconductor package having field effect transistors (FETs) with a back-gate feature. The thermally enhanced semiconductor package includes a first buried oxide (BOX) layer, a first epitaxial layer over the first BOX layer, a second BOX layer over the first epitaxial layer, a second epitaxial layer over the second BOX layer and having a source, a drain, and a channel between the source and the drain, a gate dielectric aligned over the channel, and a front-gate structure over the gate dielectric. Herein, a back-gate structure is formed in the first epitaxial layer and has a back-gate region aligned below the channel. A FET is formed by the front-gate structure, the source, the drain, the channel, and the back-gate structure.