Josephson effect in Nb/two-dimensional electron gas structures using a pseudomorphic InxGa1−xAs/InP heterostructure

Abstract

Superconducting Nb–In0.53Ga0.47As/In0.77Ga0.23As/InP–Nb contacts with an electrode separation of 450 nm were fabricated. Due to the high mobility of the two-dimensional electron gas, the current transport can be described within the clean limit regime. At 0.3 K a critical current of 3.8 μA was obtained for 6 μm wide contacts leading to a characteristic voltage of 190 μV. The decrease of the critical current with increasing temperature can be explained by a theory developed by A. Chrestin, T. Matsuyama, and U. Merkt [Phys. Rev. B 49, 498 (1994)], which takes δ-shaped barriers at the superconductor/semiconductor interfaces into account.

Josephson coupling through one-dimensional ballistic channel in semiconductor-superconductor hybrid quantum point contacts

“…25 As QPC with Nb electrodes is examined. The quantization of I c is demonstrated by the staircase variation of I sw .…”

“…A direct measurement of normal-metal electronic temperature in an Al/Cu JJ demonstrates that the temperature increases once the JJ switches from a superconducting state to a resistive state which results in the reduction of I r 22 . Moreover, Sc/Sm hybrid JJs in general show a temperature independent I r in the temperature range where its I-V curve shows hysteresis [23][24][25] , indicating that I r is suppressed in low-temperature limit due to the increased temperature by heating. As shown later in Fig.…”

Current-voltage characteristics of semiconductor-coupled superconducting weak links with large electrode separations

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Much of that interest was stimulated by the 1978/1980 papers of Silver et al 17 and Clark et al, 18 who proposed three-terminal gate-modulatable weak-link devices, referred to as hybrid Josephson field effect transistors, or briefly JOFETs. These devices draw on the ability to modulate the electron concentration in a thin semiconductor layer via a gate electrode, and thereby modulate the Josephson critical current.…”

Spectroscopic measurements on the Andreev reflection probability as a function of temperature

“…10 While the agreement between theory and experiment is excellent for low temperatures (TϽ2 K), the theory predicts larger values of I C than observed for T above 2 K. The authors 9 attribute this discrepancy to the uncertainty in the determination of the critical current due to smearing of the I -V characteristic in this temperature range. However, the data seem to suggest a vanishing critical current for TϷ4 K, a value much smaller than the critical temperature of 8.9 K. 9 The process mediating the phase information between the two superconductors-and thus generating a supercurrent through the normal conductor-is the so-called Andreev reflection. 11 The Andreev reflection coefficient A(E,T) gives the probability for electrons being retroreflected as holes when impinging on a superconductor/normal-metal interface ͑SN interface͒.…”