Near-field Optical Spectroscopy and Microscopy of Laterally Coupled Quantum Dots: Bonding and Antibonding States

TL;DR

This study uses near-field optical spectroscopy and microscopy to investigate the bonding and antibonding states of laterally coupled quantum dots, revealing energy splitting and spatial distribution with high resolution.

Contribution

It demonstrates a high-resolution, non-invasive method to analyze coupled quantum dots' electronic states and spatial properties without complex sample fabrication.

Findings

Observation of split photoluminescence spectra indicating bonding and antibonding states

Spatial mapping confirms the proximity and coupling of quantum dots

Qualitative agreement with simple two-dimensional potential model

Abstract

We report on high-resolution photoluminescence (PL) spectroscopic and microscopic study of laterally coupled InAs/GaAs self-assembled quantum dots by using a low-temperature near-field scanning optical microscope. We have observed slightly split PL spectra, which are associated with the bonding (symmetric) and antibonding (antisymmetric) energy states between two coupled quantum dots, closely located each other as confirmed by spatial mapping of the PL intensity. The experimental results are in qualitative agreement with the simple theoretical calculations based on a two-dimensional potential model. This work may open the way to a simultaneous spectroscopy and microscopy study of laterally coupled quantum dots in a high-density quantum dot sample without any articulate sample fabrication.