Resonant 2D-2D tunneling with account for spin-orbit interaction

TL;DR

This paper develops a theory for 2D-2D tunneling considering spin-orbit interaction, analyzing experimental data and proposing new heterostructures where SOI effects could be observed.

Contribution

It introduces a detailed theoretical model for tunneling with SOI and identifies conditions and structures suitable for experimental detection of SOI effects.

Findings

Resonant tunneling peaks are observed experimentally in GaAs/AlGaAs heterostructures.

SOI effects are more detectable in hole tunneling than in electron tunneling.

Strained SiGe heterostructures are promising candidates for observing SOI in 2D-2D tunneling.

Abstract

We present a theory of quantum tunneling between 2D layers with account for Rashba and Dresselhaus spin-orbit interaction (SOI) in the layers. Energy and momentum conservation results in a single resonant peak in the tunnel conductance between two 2D layers as has been experimentally observed for two quantum wells (QW) in GaAs/AlGaAs heterostructures. The account for SOI in the layers leads to a complex pattern in the tunneling characteristic with typical features corresponding to SOI energy. For this manifestation of SOI to be observed experimentally the characteristic energy should exceed the resonant broadening related to the particles quantum lifetime in the layers. We perform an accurate analysis of the known experimental data on electron and hole 2D-2D tunneling in AlGaAs/GaAs heterostructures. It appears that for the electron tunneling the manifestation of SOI is difficult to observe, but for the holes tunneling the parameters of the real structures used in the experiments are very close to those required by the resolution criteria. We also consider a new promising candidate for the effect to be observed, that is p-doped SiGe strained heterostructures. The reported parameters of cubic Rashba SOI and quantum lifetime in strained Ge QWs fabricated up to date already match the criteria for observing SOI in 2D-2D heavy holes tunneling. As supported by our calculations small adjustments of the parameters for AlGaAs/GaAs p-type QWs or simply designing a 2D-2D tunneling experiment for SiGe case are very likely to reveal the SOI features in the 2D-2D tunneling.