Length dependence of quantized conductance in etched GaAs/AlGaAs quantum wires

Quantum wires with strong lateral confinement fabricated by high resolution electron beam lithography and wet chemical etching show conductance quantization up to a length comparable to the mean free path of the electrons associated with respective 2DEGs. By the temperature dependence of the quantized conductance an energy-spacing, ΔE_1D=12.5±0.5 meV, between the two lowest lying 1D subbands for 135 nm wide wires was found-about 5 times larger than in commonly used split-gate devices. The breakdown of conductance quantization with increasing wire length is studied for quantum wires fabricated from wafers with different mobilities between 0.05×10 ⁶ and 2×10⁶ cm²Ns. Our results support the suggestion by Koester et al. (1996), that backscattering is suppressed in strongly confined quantum wires, where the 1D subband energy spacing is much larger than the random potential fluctuations in the sample