Disclosed are embodiments of a structure that comprises a first device, having multiple FETs, and a second device, having at least one FET. Sections of a first portion of a semiconductor layer below the first device are doped and contacted to form back gates. A second portion of the semiconductor layer below the second device remains un-doped and un-contacted and, thus, functions as an insulator. Despite the performance degradation of the first device due to back gate capacitance, the back gates result in a net gain for devices such as, SRAM cells, which require precise Vt control. Contrarily, despite marginal Vt control in the second device due to the absence of back gates, the lack of capacitance loading and the added insulation result in a net gain for high performance devices such as, logic circuits.