A transistor device is provided that includes a gate electrode disposed between source and drain electrodes and overlying a quantum dot structure realized by a modulation doped quantum well structure. A potential barrier surrounds the quantum dot structure. The transistor device can be configured for operation as a single electron transistor by means for biasing the gate and source electrodes to allow for tunneling of a single electron from the source electrode through the potential barrier surrounding the quantum dot structure and into the quantum dot structure, and means for biasing the gate and drain electrodes to allow for selective tunneling of a single electron from the quantum dot structure through the potential barrier surrounding the quantum dot structure to the drain electrode, wherein the selective tunneling of the single electron is based upon spin state of the single electron.