Dissociation of one-dimensional excitons by static electric field

TL;DR

This paper theoretically investigates how a static electric field affects one-dimensional excitons, showing that strong fields cause exciton dissociation and the emergence of Wannier-Stark ladder features in optical spectra.

Contribution

It provides a detailed analysis of exciton behavior under static electric fields in one-dimensional semiconductors, highlighting the transition from bound states to continuum and the spectral signatures of dissociation.

Findings

Weak fields cause a quadratic redshift of exciton absorption.

Strong fields lead to exciton dissociation and Wannier-Stark ladder formation.

Optical spectra can be used to experimentally detect exciton dissociation.

Abstract

The quantum states of an electron-hole pair in one-dimensional semiconductors under a static electric field are theoretically analyzed using a two-band model with on-site Coulomb interaction. In the absence of static field, the electron and hole are always bound, forming an exciton regardless of the Coulomb interaction strength, in contrast to what occurs in higher-dimensional semiconductors. The static field modifies the wave function of the electron-hole pair, turning bound states into continuum states. However, at low static fields, the linear optical spectra resemble those of the unbiased semiconductor, exhibiting a quadratic redshift of the main exciton absorption line as the field increases. When the static field exceeds a critical threshold, the exciton dissociates and the linear optical spectra exhibit signatures of the Wannier-Stark ladder with squally spaced peaks, making them a valuable tool for experimentally probing exciton dissociation.