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Abstract Understanding the coexistence, competition and/or cooperation between superconductivity and charge density waves (CDWs) in the transition metal dichalcogenides (TMDs) is an elusive goal which, when realized, promises to reveal fundamental information on this important class of materials. Here, we use four-terminal current-voltage measurements to study the Van der Waals interface between freshly exfoliated flakes of the high-T c superconductor, Bi-2212, and the CDW-dominated TMD layered material, 1T-TaS2. For highly transparent barriers, there is a pronounced Andreev reflection feature providing evidence for proximity-induced high-T c superconductivity in 1T-TaS2 with a surprisingly large energy gap (~20 meV) equal to half that of intrinsic Bi-2212 (~40 meV). Our systematic study using conductance spectroscopy of junctions with different transparencies also reveals the presence of two separate boson modes, each associated with a “dip-hump” structure. We infer that the proximity-induced high-T c superconductivity in the 1T-TaS2 is driven by coupling to the metastable metallic phase coexisting within the Mott commensurate CDW (CCDW) phase and associated with a concomitant change of the CCDW order parameter in the interfacial region.

We report on a low temperature study of Schottky barriers between Au, Cr or Al electrodes deposited directly onto moderately-doped Si or GaAs substrates with doping densities in the range cm−3 and find the unexpected result that for temperatures 150 K both the zero-voltage Schottky barrier height, and the reciprocal ideality factor, , have linear temperature dependences that extrapolate to zero at T  =  0. Accordingly, the thermionic emission equation with these modified temperature-dependent parameters gives a good description of the current–voltage (I–V) characteristics at temperatures where thermionic field emission and field emission (direct tunneling) in addition to thermionic emission are known to be important. Our analysis utilizes a barrier inhomogeneity model to show that the temperature-independent product determined from forward bias characteristics defines a flat band voltage which is shown to be equivalent to the built-in voltage separately determined by extrapolation of capacitance versus voltage measurements made in the reverse bias region. [ABSTRACT FROM AUTHOR]