Infrared transmission spectroscopy of charge carriers in self-assembled InAs quantum dots under surface electric fields

TL;DR

This study uses infrared transmission spectroscopy to investigate charge carrier energy levels in self-assembled InAs quantum dots, revealing how surface electric fields influence their electronic structure without external magnetic fields.

Contribution

It introduces a method combining FTIR spectroscopy with electrostatic gating to analyze intersublevel spacings in quantum dots under surface electric fields.

Findings

Intersublevel spacings match theoretical calculations for electrons and holes.

Surface electric fields modulate charge carrier energy levels.

Enhanced intersubband resonances observed due to quantum dot layer.

Abstract

We present a study on the intersublevel spacings of electrons and holes in a single layer of InAs self-assembled quantum dots (SAQDs) using Fourier transform infrared (FTIR) transmission spectroscopy without the application of an external magnetic field. Epitaxial, complementary-doped and semi-transparent electrostatic gates are grown within the ultra high vacuum conditions of molecular beam epitaxy to voltage-tune the device, while a two dimensional electron gas (2DEG) serves as back contact. Spacings of the hole sublevels are indirectly calculated using the photoluminescence spectroscopy along with FTIR spectroscopy. The observed spacings fit well to the calculated values for both electrons and holes. Additionally, the intersubband resonances of the 2DEG are enhanced due to the QD layer on top of the device.