Unusual Tunneling Characteristics of Double-quantum-well Heterostructures

TL;DR

This paper investigates unusual tunneling behaviors in double quantum well heterostructures, revealing a violation of in-plane momentum conservation and highlighting the role of emitter-well correlations and Landau level tunneling.

Contribution

It demonstrates that tunneling current is primarily influenced by emitter-well correlation rather than well-to-well, challenging conventional models of 2D tunneling.

Findings

Tunneling current depends mainly on emitter-well correlation.

Magnetic field reveals Landau level tunneling channels.

Evidence of in-plane momentum conservation violation.

Abstract

We report tunneling phenomena in double In$_{0.53}$Ga$_{0.47}$As quantum-well structures that are at odds with the conventional parallel-momentum-conserving picture of tunneling between two-dimensional systems. We found that the tunneling current was mostly determined by the correlation between the emitter and the state in one well, and not by that between those in both wells. Clear magnetic-field-dependent features were first observed before the main resonance, corresponding to tunneling channels into the Landau levels of the well near the emitter. These facts provide evidence of the violation of in-plane momentum conservation in two-dimensional systems.