Locating environmental charge impurities with confluent laser spectroscopy of multiple quantum dots

TL;DR

This study employs resonant laser spectroscopy on multiple quantum dots to spatially identify charge impurities, revealing residual carbon dopants as a key source of charge fluctuations in quantum dot structures.

Contribution

It introduces a method to locate environmental charge impurities near quantum dots using resonant laser spectroscopy and maps their effects to specific dopants.

Findings

Charge fluctuators are identified near quantum dots.

Residual carbon dopants are major charge trap sources.

Spectral discontinuities correlate with charging events.

Abstract

We used resonant laser spectroscopy of multiple confocal InGaAs quantum dots to spatially locate charge fluctuators in the surrounding semiconductor matrix. By mapping out the resonance condition between a narrow-band laser and the neutral exciton transitions of individual dots in a field effect device, we identified spectral discontinuities as arising from charging and discharging events that take place within the volume adjacent to the quantum dots. Our analysis suggests that residual carbon dopants are a major source of charge-fluctuating traps in quantum dot heterostructures.