Spectral analysis on a phonon spectral function of a solid-state plasma in a doped semiconductor

TL;DR

This paper analyzes the spectral function of phonons in a doped semiconductor plasma, focusing on plasmon-phonon interactions and their temperature-dependent behavior, with applications to GaN conduction electrons.

Contribution

It provides a detailed theoretical analysis of phonon spectral functions considering carrier screening and plasmon-phonon coupling in doped semiconductors, including temperature effects.

Findings

Dispersion relations of coupled plasmon-phonon modes are characterized.

Carrier-phonon interactions significantly affect phonon energy shifts and broadening.

Results are specifically applied to conduction electrons in wurtzite GaN.

Abstract

We report an analysis on a phonon spectral function of a solid-state plasma formed in a doped semiconductor. Real and imaginary parts of phonon propagators are evaluated including carrier screening effects within a random phase approximation, and finite-temperature spectral behavior of the phonon spectral function is examined in terms of plasmon--phonon coupled modes and quasiparticle excitation mode of the plasma. The results are applied to the case of conduction electrons in a wurtzite GaN considering carrier-phonon coupling channel via polar optical phonons. We show that the dispersion relations of the plasmon-LO phonon coupled (`upper' and `lower') modes and the character of the additional modes via single quasiparticle excitations are heavily associated with the nonlocal and dynamic behavior of the energy shift and collisional broadening of the dressed phonon propagator of the plasma.