Polaron-induced lattice distortion of (In,Ga)As quantum dots by optically excited carriers

TL;DR

This study uses high-resolution x-ray diffraction to reveal how optically injected carriers in (In,Ga)As quantum dots cause specific lattice distortions, including tetragonal expansion due to polaron formation.

Contribution

It provides direct experimental evidence of polaron-induced lattice distortion in quantum dots using high-resolution x-ray diffraction.

Findings

Tetragonal lattice expansion along [001] axis observed

Isotropic expansion attributed to lattice heating

Polaron formation causes femtometer-scale lattice distortion

Abstract

We report on a high resolution x-ray diffraction study unveiling the effect of carriers optically injected into (In,Ga)As quantum dots on the surrounding GaAs crystal matrix. We find a tetragonal lattice expansion with enhanced elongation along the [001] crystal axis that is superimposed on an isotropic lattice extension. The isotropic contribution arises from excitation induced lattice heating as confirmed by temperature dependent reference studies. The tetragonal expansion on the femtometer scale is attributed to polaron formation by carriers trapped in the quantum dots.