Tunneling Spectrum And Shot Noise In A Normal Metal/semiconductor/d-wave Superconductor Junction

The shot noise is a consequence of the discrete nature of the charge carriers. The measurement of the shot noise can provide information on the conduction process not contained in conductance. In the last few years, much attention has been paid to the study of shot noise in the mesoscopic systems.Our model considered in this work is a normal metal/semiconductor/d-wave supercon- ductor tunnel junction system. The left electrode is the normal metal, the right one is the d-wave superconductor, and the middle part is the semiconductor. Based on the Bogoliubov-de Genner (BdG) equation and Blonder-Tinkhanr-Klapwijk (BTK) theory, the tunneling spectrum and the shot noise were studied through N/SM/S structure with Landauer-Büttiker formula. As we simulate that the semiconductor is considered as a certain thickness barrier, the results will be more reasonable. The results are as follows:1.Under a certain Rashba spin-orbit coupling parameter, the relation between the shot noise, the tunneling spectrum and the bias was discussed. The result indicated that the electron-injection angle and d-wave superconductivity pair potential may affect the shot noise and the tunneling spectrum. A sizable areal density of midgap states exists on {110} surface of d-wave superconductor. The Andreev reflection conductance is two times as the normal tunneling conductance. The shot-noise spectroscopy is seriously influenced by the surface electronic states of the d-wave superconductor. When the width of semiconductor is integral multiples of 3ε0, the behaviors of tunneling spectrum are qualitatively different from that of shot noise when the width of semiconductor is not integral multiples of 3ε0.2.We considered the effect of semiconductor width on shot noise and tunneling spectrum under a certain Rashba spin-orbit coupling parameter. When the width of the semiconductor increases, the number of the resonance peaks of the shot noise spectrum change. The current depends on the electron-injection angle. The peaks of the current appear, the current is suppressed well, and the conductance increases, with the width of the semiconductor increasing. 3.We stdudied the shot noise and the tunneling spectrum when the Rashba spin-orbit coupling existed. The result showes that the existence of the Rashba spur-orbit coupling does not affect shot noise and tunneling spectrum obviously.