Reflectionless tunneling in planar Nb/GaAs hybrid junctions

Giazotto, Francesco; Cecchini, Marco; Pingue, Pasqualantonio; Beltram, Fabio; Lazzarino, Marco; Orani, Daniela; Rubini, Silvia; Franciosi, Alfonso
March 2001
Applied Physics Letters;3/19/2001, Vol. 78 Issue 12, p1772
Academic Journal
Reflectionless tunneling was observed in Nb/GaAs superconductor/semiconductor junctions fabricated by a two-step procedure. First, periodic δ-doped layers were grown by molecular-beam epitaxy near the GaAs surface, followed by an As cap layer to protect the surface during ex situ transfer. Second, Nb was deposited by dc-magnetron sputtering onto a GaAs(001) 2x4 surface in situ after thermal desorption of the cap layer. The magnetotransport behavior of the resulting hybrid junctions was successfully analyzed within the random matrix theory of phase-coherent Andreev transport. The impact of junction morphology on reflectionless tunneling and the applicability of the fabrication technique to the realization of complex superconductor/semiconductor mesoscopic systems are discussed. © 2001 American Institute of Physics.


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