Quantized conductance in a split-gate point contact based on a pseudomorphic InGaAs/InP heterostructure

In this paper the fabrication and characterization of split-gate point contacts based on a pseudomorphic InGaAs/InP heterostructure with an indium content of 77% in the strained channel layer is described. Steps in the conductance were observed, which are due to quantized conductance through the quasi one-dimensional constriction formed by the split-gates. Deviations from the ideal quantization are studied by applying differing bias voltages on the two fingers forming the point contact. Since the channel layer of our structure consists of a ternary material it is argued that, beside impurity and interface roughness scattering, alloy scattering processes contribute significantly to the observed deviations of the ideal quantized conductance.