Transport properties in an InAs-inserted-channel In0.52Al0.48As/In0.53Ga0.47As heterostructure coupled superconducting junction

Supercurrent is observed in a superconductor-semiconductor-superconductor (S-Sm-S) junction using a two-dimensional-electron-gas system in an InAs-inserted-channel In0.52Al0.48As/In0.53Ga0.47As heterostructure. The temperature dependence of the supercurrent cannot be explained by a simple exponential expression, but is here explained in terms of the clean-limit theory, taking account of the higher-order effect of the coherence length. The differential resistance of the junction shows clear subharmonic energy-gap structures due to multiple Andreev reflection since the phase coherence is maintained during the Andreev-reflection process. The Cooper pair transport explained by the clean-limit theory is attributed to the fact that the mean free path is longer than the coherence length and the length between the superconducting electrodes.