Quantized conductance in extended electron waveguides fabricated on shallow etched modulation-doped GaAs/AlGaAs heterostructures

By high-resolution electron beam lithography and wet chemical etching extended electron waveguides with lengths up to View the MathML source were fabricated on modulation-doped GaAs/AlGaAs heterostructures showing conductance quantization. For short electron waveguides 15 well-resolved steps in the conductance trace are observable. Conductance quantization is observed up to wire lengths comparable to the transport mean free path of electrons in the unconstrained two-dimensional electron gas, indicating that scattering due to fabrication induced defects is negligible in the present structures. By an analysis of temperature-dependent measurements the one-dimensional subband spacings are determined to be greater than 10 meV.