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. Step s in the conductance were observed, which are due to quantized conduct ance through the quasi one-dimensional constriction formed by the spli t-gates. Deviations from the ideal quantization are studied by applyin g differing bias voltages on the two fingers forming the point contact . Since the channel layer of our structure consists of a ternary mater ial it is argued that, beside impurity and interface roughness scatter ing, alloy scattering processes contribute significantly to the observ ed deviations of the ideal quantized conductance. (C) 1996 American In stitute of Physics.