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[3]Carrier Transport in Mesoscopic Semiconductor Heterojunction Coupled to Superconducting Junctions:
The conductance of a mesoscopic device is studied under the effect of an external electric field. Two different models are considered: ( i ) The 2DEG is constrained to a Q1D-channel, separated from the superconducting reservoirs by a quantum point contact controlled by the gates. (ii) the second model is constructed as a quantum dot coupled to a superconducting leads via a quantum point contact. The conductance is expressed in terms of both the normal tunneling and the Andreev-reflection processes. For the first model, the conductance exhibits a peak as a function of the bias voltage under the effect of the electric field. This peak changes sign when the direction of the electric field changes. This trend is due to the chaotic behavior of the considered mesoscopic device. Also, for a second model, the dependence of the maximum value of the conductance with the electric field is a nonlinear trend. The combination of Andreev-reflection with resonant transmission through the discrete levels would give rise to a rich information about the subgap harmonic structure in the conductance –bias voltage characteristics.
