Two-fluid hydrodynamic model for semiconductors

TL;DR

This paper introduces a two-fluid hydrodynamic model for semiconductors with multiple charge carriers, predicting new optical modes and spectral features not captured by traditional models.

Contribution

The paper develops a two-fluid hydrodynamic model for semiconductors, extending nonlocal Mie theory to include two plasmas and revealing novel optical modes.

Findings

Prediction of acoustic and optical longitudinal modes in semiconductors.

Identification of new peaks in extinction spectra due to the acoustic mode.

Extension of nonlocal Mie theory to two-fluid systems.

Abstract

The hydrodynamic Drude model (HDM) has been successful in describing the optical properties of metallic nanostructures, but for semiconductors where several different kinds of charge carriers are present, an extended theory is required. We present a two-fluid hydrodynamic model for semiconductors containing electrons and holes (from thermal or external excitation) or light and heavy holes (in $p$-doped materials). The two-fluid model predicts the existence of two longitudinal modes, an acoustic and an optical, whereas only an optical mode is present in the HDM. By extending nonlocal Mie theory to two plasmas, we are able to simulate the optical properties of two-fluid nanospheres and predict that the acoustic mode gives rise to peaks in the extinction spectra that are absent in the HDM.