Ballistic Three-Branch Nanojunctions Realized With Self-Aligning Mask
Ramamoorthy, Harihara Sudhahar
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An experimental study of the nonlinear properties of a ballistic three-branch junction is presented. Ballistic electron transport in these devices is responsible for a nonlinear input-output transfer curve that has been exploited in the literature for applications such as signal rectification, frequency multiplication and designing logic gates. The devices studied here were fabricated using a self-aligning mask technique that is expected to provide improvements over conventional electron-beam resist masks. Electrical measurements were carried out in a two-input passive mode where finite voltages V l and V r are applied in a push-pull manner (V l =V and V r =−V) to the left and right terminals, respectively, of the junction. The output of the central probe voltage V C was found to be rectifying at all values of the applied voltage, consistent with earlier work. V C evolved from a parabolic dependence, V c ∝ −V l,r 2 , indicative of ballistic rectification, to a linear one at higher biases, indicative of strong energy relaxation. Temperature dependent studies of the dependence of V C on bias were also performed. At 77 K, the time-dependent variation of V C under zero applied bias revealed some evidence of charge leakage from a Coulomb island, formed unintentionally in the center of the three-branch junction. This behavior may suggest new avenues for the development of nanoelectronic logic and memory devices.