INPLANE GATES AND NANOSTRUCTURES FABRICATED BY DIRECT OXIDATION OF SEMICONDUCTOR HETEROSTRUCTURES WITH AN ATOMIC-FORCE MICROSCOPE

The surface of shallow Ga[Al]As heterostructures is locally oxidized w ith an atomic Force microscope. The electron gas underneath the oxide is depleted. We demonstrate experimentally that these depleted regions of the two-dimensional electron gas can be made highly resistive at l iquid nitrogen temperatures. Thus, local anodic oxidation of high elec tron mobility transistors with an atomic force microscope provides a n ovel method to define nanostructures and in-plane gates. Two examples, namely antidots and quantum point contacts as in-plane gate transisto rs have been fabricated and their performance at low temperatures is d iscussed. (C) 1998 American Institute of Physics. [S0003-6951 (98)0402 8-5].