GLYPH<s49>GLYPH<s46> GLYPH<s53> GLYPH<s50>GLYPH<s46> GLYPH<s48> GLYPH<s50>GLYPH<s46> GLYPH<s53> GLYPH<s51>GLYPH<s46> GLYPH<s48> GLYPH<s55>GLYPH<s48> GLYPH<s56>GLYPH<s48> GLYPH<s57>GLYPH<s48> GLYPH<s50> GLYPH<s51> GLYPH<s52> GLYPH<s53> GLYPH<s54> GLYPH<s55> GLYPH<s56> GLYPH<s49> GLYPH<s50> GLYPH<s51> GLYPH<s45>GLYPH<s51> GLYPH<s48> GLYPH<s51> GLYPH<s48> GLYPH<s49> GLYPH<s48> GLYPH<s48> GLYPH<s50> GLYPH<s48> GLYPH<s48> GLYPH<s54>GLYPH<s75> GLYPH<s55>GLYPH<s75> GLYPH<s54>GLYPH<s46>GLYPH<s53>GLYPH<s75> GLYPH<s53>GLYPH<s75> GLYPH<s52>GLYPH<s46>GLYPH<s53>GLYPH<s75> GLYPH<s52>GLYPH<s75> GLYPH<s51>GLYPH<s75> GLYPH<s100>GLYPH<s86>GLYPH<s47>GLYPH<s100>GLYPH<s73>GLYPH<s32>GLYPH<s40> GLYPH<s41> GLYPH<s86>GLYPH<s111>GLYPH<s108>GLYPH<s116>GLYPH<s97>GLYPH<s103>GLYPH<s101>GLYPH<s32>GLYPH<s40>GLYPH<s109>GLYPH<s86>GLYPH<s41> GLYPH<s50>GLYPH<s75> GLYPH<s40>GLYPH<s97>GLYPH<s41> GLYPH<s32> GLYPH<s80>GLYPH<s101>GLYPH<s97>GLYPH<s107>GLYPH<s32>GLYPH<s112>GLYPH<s111>GLYPH<s115>GLYPH<s105>GLYPH<s116>GLYPH<s105>GLYPH<s111>GLYPH<s110>GLYPH<s32>GLYPH<s40>GLYPH<s109>GLYPH<s101>GLYPH<s86>GLYPH<s41> GLYPH<s84> GLYPH<s101>GLYPH<s109>GLYPH<s112>GLYPH<s101>GLYPH<s114>GLYPH<s97>GLYPH<s116>GLYPH<s117>GLYPH<s114>GLYPH<s101>GLYPH<s32>GLYPH<s40>GLYPH<s75>GLYPH<s41> GLYPH<s40>GLYPH<s98>GLYPH<s41> GLYPH<s50> GLYPH<s40>GLYPH<s84> GLYPH<s41> GLYPH<s32> GLYPH<s100> GLYPH<s86>GLYPH<s47> GLYPH<s100> GLYPH<s73> GLYPH<s32> GLYPH<s40> GLYPH<s41> GLYPH<s32>GLYPH<s86>GLYPH<s32>GLYPH<s40>GLYPH<s109> GLYPH<s86>GLYPH<s41> GLYPH<s50>GLYPH<s75> GLYPH<s45>GLYPH<s54> GLYPH<s45>GLYPH<s52> GLYPH<s45>GLYPH<s50> GLYPH<s48> GLYPH<s50> GLYPH<s52> GLYPH<s54> GLYPH<s45>GLYPH<s50>GLYPH<s48>GLYPH<s48> GLYPH<s45>GLYPH<s49>GLYPH<s48>GLYPH<s48> GLYPH<s48> GLYPH<s49>GLYPH<s48>GLYPH<s48> GLYPH<s50>GLYPH<s48>GLYPH<s48> GLYPH<s45> GLYPH<s48>GLYPH<s46> GLYPH<s53> GLYPH<s48>GLYPH<s46> GLYPH<s48> GLYPH<s48>GLYPH<s46> GLYPH<s53> GLYPH<s45> GLYPH<s53>GLYPH<s48> GLYPH<s48> GLYPH<s53>GLYPH<s48> GLYPH<s51>GLYPH<s46> GLYPH<s53>GLYPH<s75> GLYPH<s51>GLYPH<s46> GLYPH<s49>GLYPH<s75> GLYPH<s50>GLYPH<s46> GLYPH<s56>GLYPH<s75> GLYPH<s84> GLYPH<s61>GLYPH<s48>GLYPH<s46> GLYPH<s56>GLYPH<s32> GLYPH<s75>GLYPH<s32> GLYPH<s86>GLYPH<s111>GLYPH<s108>GLYPH<s116>GLYPH<s97>GLYPH<s103>GLYPH<s101>GLYPH<s32>GLYPH<s40> GLYPH<s86>GLYPH<s41> GLYPH<s67>GLYPH<s117>GLYPH<s114>GLYPH<s114>GLYPH<s101>GLYPH<s110>GLYPH<s116>GLYPH<s32>GLYPH<s40> GLYPH<s65>GLYPH<s41> GLYPH<s50>GLYPH<s75>GLYPH<s32> GLYPH<s51>GLYPH<s46> GLYPH<s57>GLYPH<s75> GLYPH<s83>GLYPH<s97>GLYPH<s109>GLYPH<s112>GLYPH<s108>GLYPH<s101>GLYPH<s32>GLYPH<s65> GLYPH<s32> GLYPH<s32> GLYPH<s83>GLYPH<s97>GLYPH<s109> GLYPH<s112>GLYPH<s108>GLYPH<s101>GLYPH<s32> GLYPH<s66> GLYPH<s84> GLYPH<s61>GLYPH<s48>GLYPH<s46> GLYPH<s55>GLYPH<s75> FIG. 2: (Color online) (a) Differential resistance dV/dI of sample A as a function of bias voltage at various tempera- tures. (b) Position of the peak assigned to 2Δ as a function of temperature. The broken line shows the expected value of 2Δ according to theory. The inset shows dV/dI at 2 K in the full bias voltage range. FIG. 1: (Color online) I − V characteristics of sample A at various temperatures. The lower right inset shows the I − V characteristics for sample B at 0.7 K. The upper left inset shows an scanning electron beam micrograph picture of sam- ple A. product of 0.11 mV. 5.7 µ A was extracted. For temperatures below 2.5 K the I − V characteristics is hysteretic. The retrapping current I r , characterized by the switching from the voltage biased state back into the superconducting state depends only slightly on temperature, with a typical value of 2.2 µ A. As can be seen in Fig. 1 (inset), for sample B a lower critical current of 0.44 µ A at 0.7 K was measured. As can be seen in Fig. 3(a), the critical current I c of sample A monotonously decreases with increasing tem- perature. A complete suppression of the Josephson su- percurrent is obtained at about 3.7 K. Up to 2 K the return current I r is almost constant at a value of approxi- mately 2.3 µ A, while at higher temperatures T ≥ 2 . 5 K I r merges with I c . A similar behavior of the retrapping cur- rent was observed previously in other Nb-semiconductor- Nb junctions. 23 As it was recently pointed out by Cour- tois et al. , 24 the hysteresis in the I − V characteristics of proximity SNS structures can be attributed to the in- crease of the normal-metal electron temperature once the junction switches to the resistive state. The differential resistance dV/dI as a function of the bias voltage close to 2Δ /e is shown in Fig. 2(a) for tem- peratures in the range from 2 to 7 K. The distinct peak and the lowering of dV/dI at its lower bias side can be at- tributed to the onset of multiple Andreev reflection. 20,21 The relatively small decrease of differential resistance at the lower bias side of the peak by about 10% compared to the higher bias side can be attributed to the presence of an interface barrier. 20,21 As can be seen in Fig. 2(b) (inset), more structures are found in the differential re- sistance by approaching zero bias. Details about these features, which we also attribute to multiple Andreev re- flection, will be given in a forthcoming publication. Fur- ther evidence that the maxima shown in Fig. 2(a) can indeed be assigned to the onset of Andreev reflection at 2Δ /e is given by the plot of the peak position as a function of temperature [cf. Fig. 2(b)], since here the peak position closely follows the theoretically expected decrease of 2Δ for an electron phonon-coupling strength of 2Δ$_{0}$ /k B T c ≃ 3 . 9. 22 Here, Δ$_{0}$ is the superconducting gap at T = 0. At a temperature of 2 K and bias volt- ages above 2Δ /e a differential resistance of 78 Ω is mea- sured. If this value is taken as the normal state resistance R N of the junction one obtains a large I c R N product of 0.44 mV. For sample B a normal state resistance of 250 Ω was measured which results in a somewhat lower I c R N From the transport data of the InN nanowires one ex- tracts an elastic mean free path of approximately 45 nm, thus the transport takes place in the diffusive regime. In addition, as stated above we have to consider the pres- ence of an interface barrier. For this case, the critical current was studied theoretically by Hammer et al. 16 In Fig. 3(a) the corresponding theoretical curve which fits best to the experimental values is plotted. We followed the approach of Dubos et al. 25 and Carillo et al. 26 by using a reduced effective Thouless energy E ∗ Th as a fit- ting parameter. The lower value of E ∗ Th = 0 . 15 meV compared to E Th = $^{ℏ}$D /L 2 = 0 . 67 meV obtained from the transport parameters is a measure of the detrimental effect of the interface resistance. 16 As can be seen in Fig. 3(b), I c ( B ) of sample A monotonously decreases with increasing magnetic field. For magnetic fields larger than 0.3 T the Josephson 2