CARRIER CONCENTRATION IN QUANTUM WIRES FABRICATED BY RACTIVE ION-BEAM ETCHING

High-quality quantum wires with a submicron width are fabricated by a combination of electron beam lithography and selective etching by reactive ion beam etching. The carrier concentrations in these wires are evaluated as a function of gate voltage by analyzing the magnetic depopulation effect observed in the quantum wire resistance. This analysis assumes a parabolic potential profile for the wire constriction. The quantum wire capacitance calculated from the carrier concentration agrees well with the capacitance measured by the 1-MHz capacitance meter. This agreement confirmes that the carrier concentration derived from the magnetoresistance gives a good estimation to the actual quasi 1-dimensional concentration.