A three-terminal switching device for use in integrated circuit devices, including a phase change material (PCM) disposed in contact between a first terminal and a second terminal; a heating device disposed in direct electrical contact between said second terminal and a third terminal, said heating device positioned proximate said PCM, and configured to switch the conductivity of a transformable portion of said PCM between a lower resistance crystalline state and a higher resistance amorphous state; and an insulating layer configured to electrically isolate said heater from said PCM material, and said heater from said first terminal.