Optically induced bistability in the mobility of a two-dimensional electron gas coupled to a layer of quantum dots

We report a bistability in the resistance of a GaAs/AlGaAs modulation doped field effect transistor in which a layer of InAs self-organized quantum do ts has been grown near the electron channel. Brief optical illumination cau ses a large, persistent drop in the two-dimensional electron gas (2DEG) res istance which can be recovered by allowing a current to flow through the Sc hottky gate. We demonstrate that illumination reduces the number of electro ns trapped in the quantum dots, lowering their potential and thereby enhanc ing the 2DEG mobility. This bistability could be the basis of an optical me mory or sensitive phototransistor. (C) 1999 American Institute of Physics. [S0003-6951(99)03305-7].