Fabrication of a quantum point contact by the dynamic plowing technique and wet-chemical etching

摘要

We have fabricated extremely confined ballisticconstrictions using a nanolithography technique based on anatomic force microscope. Vector-scan controlled dynamic plowingwith the vibrating tip enables to plastically indent a thin resist layeralong a prearranged path. Transfer of the resist pattern into thesemiconductor substrate is achieved by a strongly diluted aqueousetchant. In this way approximately 30 nm deep gooves were etchedin the channel area of a modulation-doped GaAs/GaAlAs field-effect transistor. The quantum point contacts were defined by abroken line whose 60 nm width represents the length and the sub-100 nm gap determines the width of the constriction. At liquid-helium temperature the conductance as a function of gate voltageshows a stepwise increase in units of 2e~2/h. Signatures of theconductance quantization persist up to 50 K, which indicates alarge subband spacing. 2000 Elsevier Science B.V. All rights reserved.