Demonstration of intricate gate,Ohmic and interconnect metallizations for nanostructure construction

We describe the fabrication and low temperature characterization of nanostructures defined by submicron-sized gate, interconnect and Ohmic metallizations on the surface of AlGaAs/GaAs heterostructures. A two level metallization architecture is used with Ohmic and gate surface patterns, separated by an inter-layer insulator, linked by patterned interconnects. The procedure, which features a 10nm alignment accuracy, can be used to interconnect metal patterns as small as 100nm. For the Ohmic metallization we discuss the injection properties of the contact as it is reduced to less than 1μm in diameter and present results which indicate the minimum size of Ohmic contacts that can be reliably formed using a Ni-Ge-Au metallization. The approach is illustrated with the fabrication and characterization of submicron-sized Corbino discs.