We report on a technique we have recently developed to fabricate very high quality gates and gated structures onInAs/AlxGa1−xSbquantum wells. The low thermal budget process leads to highly stable gates with extremely low leakage currents. Both electron and hole concentrations can be changed over a wide range by the application of modest gate voltages. We obtain adn/dVvalue of5×1011 cm2/Vfor electrons and1.6×1012 cm2/Vfor holes at 1.2 K. ©1998 American Institute of Physics.