Keynote
HYBRID SEMICONDUCTOR-SUPERCONDUCTOR DEVICES

Interest in the superconducting proximity effect has been reinvigorated recently by novel optoelectronic applications as well as by the possible emergence of the elusive Majorana fermion.

We proposed an efficient approach for generation of entangled photons, based on Cooper-pair luminescence in semiconductors, which does not require isolated emitters such as single atoms or quantum dots. We also proposed and analyzed theoretically a new effect of enhanced light amplification in electrically-driven semiconductor-superconductor structures, including Cooper-pair based two-photon gain.

We demonstrated experimentally hybrid high-Tc-superconductor-semiconductor tunnel junctions. The devices were fabricated by the newly-developed mechanical bonding technique, resulting in high-Tc-semiconductor planar junctions acting as superconducting tunnel diodes. The devices were characterized by electrical transport measurements. We also showed similar nonlinearity and excess voltage in graphite based junctions and junctions based on topological insulator Bi2Te3.

We produced high-temperature superconductivity in topological insulators Bi2Se3 and Bi2Te3 via proximity to Bi2Sr2CaCu2O8+δ, in order to access increasing temperature and energy scales for this phenomenon. This was achieved by a new mechanical bonding technique we developed, enabling the fabrication of high-quality junctions between materials, unobtainable by conventional approaches – and characterized by electrical transport measurements. We observed proximity-induced superconductivity in Bi2Se3 and Bi2Te3 persisting up to at least 80K – a temperature an order of magnitude higher than any previous observations. These results open new directions for fundamental studies in condensed matter physics and enable a wide range of applications in spintronics and quantum computing.