In this study, a Pt/GaSb Schottky diode with impressive rectifying behavior is used for the first time in the fabrication of a GaSb p-channel Schottky-barrier metal-oxide-semiconductor field-effect transistor (MOSFET). A gate-last integration scheme was employed to fabricate the MOSFET. Compared with a MOSFET with a Ni-alloy source and drain (S/D), the MOSFET with a Pt-alloy S/D can endure higher thermal stress during atomic layer deposition at 250 °C for 1 h without significant junction degradation. This high endurance to thermal stress is because Pt alloy has a lower reactivity to GaSb and a higher crystallization temperature. As a result, a record high ON/OFF ratio of 3× 104 is reported for the GaSb Schottky-barrier MOSFET; an effective hole mobility of approximately 82 cm2V-1s-1 is achieved.