Reflection of Electrons during Tunneling and an Intersubband Polaron in the 2D Electron System of a Delta-Layer in GaAs

TL;DR

This paper investigates electron reflection phenomena during tunneling in delta-doped GaAs structures, revealing how intersubband transitions and LO-phonon emissions influence tunneling behavior and polaron formation.

Contribution

It demonstrates the dominance of reflection processes during intersubband polaron resonance and clarifies conditions for observing reflection in tunneling involving multiple subbands.

Findings

Reflection occurs at LO-phonon emission threshold during tunneling.

Intersubband polaron resonance enhances reflection processes.

Reflection observed when two subbands are occupied during tunneling.

Abstract

Al-$\delta$-GaAs structures are studied where tunneling to one or more subbands of the 2D electron system of a near-surface delta-doped layer is observed. Reflection of electrons at the threshold of the emission of LO-phonon is observed. This phenomenon occurs when a new subband is involved in the tunneling process and when intersubband transitions of the electrons in a 2D-system with the emission of LO-phonon are added to the inelastic tunneling within a single subband. It is shown that, under the conditions of an intersubband polaron resonance, the reflection processes dominate during tunneling into the delta-layer. If, however, tunneling from the delta-layer occurs, the reflection processes are observed when two subbands are occupied.