One-dimensional subbands and mobility modulation in GaAs/AlGaAs quantum wires

Abstract

Devices consisting of 100 parallel, modulation-doped GaAs/AlGaAs wires, each about 40 nm wide, have been fabricated and tested at 4.2 and 77 K. The wires were created by ion milling a shallow grating into the doped AlGaAs layer. The mask for etching the grating was produced by x-ray nanolithography, and lift-off of Ti/Au. The grating period was 200 nm and the linewidth about 85 nm. Backgate bias or illumination was used to modulate the charge density in the wires. Conductance measurements at 4.2 K provide clear evidence of quasi-one-dimensional density of states. A corresponding modulation of the electron mobility, above and below values in the two-dimensional system, was observed.