Quantum Mechanical Transmission and Reflection of Quasi-Particles at Arbitrary Potential Barriers in the Superconducting Base Transistor

Abstract

We propose a systematic method for calculating the quasi-particle transmission, T, and reflection, R, probabilities at the arbitrary potential barrier, by using multistep potential approximation. T and R were calculated from first principles using the Bogoliubov equations of motion. For the N/I/S emitter-base tunneling junction and base-collector heterojunction in the superconducting base transistor, T and R were computed as functions of quasi-particle energy, potential barrier height and width. In the case of the YBCO/n-InGaAs base-collector heterojunction with a Schottky barrier height of 70 meV, it was found that T was greater than 0.5. This suggests that a combination of YBCO and n-InGaAs is suitable for use in the base-collector heterojunction of a superconducting base transistor. We also show I-V curves for the N/I/S tunneling junction.