Transport in Nb-InGaAs Contacts
Most contacts between superconductors (S) and semiconductors (Sm) include an insulating Schottky barrier (I), and tnerefore behave as SIN tunnel junctions (N is normal metal). We describe recent experiments which explore the role of such contacts in SSmS (SINIS) weak links. As contact transmittance increases, a crossover occurs from tunneling to metallic behavior, due to a rapid increase in the current contributed by pair-quasiparticle conversion. SSmS devices do not behave simpiv as two SSm contacts in series, due in part to the non-equilibrium nature ot the quasiparticle distribution in the normal material. The two-dimensional geometry of the device structure is also important. The current experimental and theoretical situation and the need for studies of single SSm contacts are discussed.
KeywordsWeak Link Andreev Reflection Contact Transparency Excess Voltage Quasiparticle Distribution
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