At least one doped semiconductor material region is formed over a crystalline insulator layer. A disposable gate structure and a planarization dielectric layer laterally surrounding the disposable gate structure are formed over the at least one doped semiconductor material region. The disposable gate structure is removed selective to the planarization dielectric layer to form a gate cavity. Portions of the at least one doped semiconductor material region are removed from underneath the gate cavity. Remaining portions of the at least one doped semiconductor material region constitute a source region and a drain region. A faceted crystalline dielectric material portion is grown from a physically exposed surface of the crystalline insulator layer. A contoured channel region is epitaxially grown on the faceted crystalline dielectric material portion. The contoured channel region increases the distance that charge carriers travel relative to a separation distance between the source region and the drain region.