Andreev reflection in engineered Al/Si/InGaAs(001) junctions

TL;DR

This paper demonstrates that inserting Si bilayers at Al/InGaAs(001) interfaces suppresses Schottky barriers, enabling high-transparency, non-alloyed Ohmic contacts suitable for superconductor-semiconductor junctions, with experimental evidence from Andreev reflection measurements.

Contribution

It introduces a novel interface engineering technique using Si bilayers to achieve transparent Ohmic contacts in Al/InGaAs junctions, advancing superconductor-semiconductor device fabrication.

Findings

Suppression of Schottky barrier in Al/InGaAs junctions.

High junction transparency close to theoretical limits.

Observation of Andreev reflection dominated transport.

Abstract

Complete suppression of the native n-type Schottky barrier is demonstrated in Al/InGaAs(001) junctions grown by molecular-beam-epitaxy. This result was achieved by the insertion of Si bilayers at the metal-semiconductor interface allowing the realization of truly Ohmic non-alloyed contacts in low-doped and low-In content InGaAs/Si/Al junctions. It is shown that this technique is ideally suited for the fabrication of high-transparency superconductor-semiconductor junctions. To this end magnetotransport characterization of Al/Si/InGaAs low-n-doped single junctions below the Al critical temperature is presented. Our measurements show Andreev-reflection dominated transport corresponding to junction transparency close to the theoretical limit due to Fermi-velocity mismatch