STM study of electrical transport properties of one dimensional contacts between MnSi similar to 1.7 nanowires and Si(111) and (110) substrates

摘要

We demonstrate the formation of contact barriers at the interfaces between MnSi1.7 nanowires (NWs) and Si substrates by the current-voltage (I-V) curves measured by scanning tunneling microscope with the tip contacting the NWs. The NWs on Si(110) exhibit linear reverse bias I-V curves, which suggests a parallel Ohmic surface state conductance of the Si(110) surface. The NWs on Si(111) exhibit nonlinear reverse bias I-V behavior, which indicates a considerable amount of minority carrier recombination-generation current. The NW length-dependence study of the forward bias current clearly shows that the quantitative change in NW length leads to a qualitative change in electrical transport properties. We derive a characteristic length L-C approximate to 200 nm and the corresponding aspect ratio of similar to 12-18 for MnSi1.7 NWs according to the variation of current density with the NW length.