This letter demonstrates, for the first time, enhancement-mode (e-mode) antimonide MOSFETs by integrating a composite high- gate stack (3 nm nm GaSb) with an ultrathin quantum well (7.5 nm). The MOSFET exhibits record high electron drift mobility of 5200 at carrier density () of , subthreshold slope of 150 mV/dec, ratio of within a voltage window of 1 V, high of 40 at of 0.5 V for a 5- gate length device. The device exhibits excellent pinchoff in the output characteristics with no evidence of impact ionization enabled by enhanced quantization and e-mode operation. RF characterization allows extraction of the intrinsic device metrics ( , , , , , and ) and the parasitic resistive and capacitive elements limiting the short-channel device performance.