The non-linear terahertz response of hot electrons in low-dimensional semiconductor superlattices: Suppression of the polar-optical phonon scattering

TL;DR

This paper investigates how suppressing inelastic polar-optical phonon scattering in low-dimensional semiconductor superlattices enhances their terahertz current responsivity, highlighting the role of electron heating and Bloch dynamics.

Contribution

It introduces a balance equations approach to analyze the terahertz response considering both elastic and inelastic scattering in low-dimensional superlattices.

Findings

Suppression of inelastic scattering greatly increases current responsivity.

Electron heating leads to a pronounced bolometric effect.

Magnetic fields and lateral quantization enhance terahertz response.

Abstract

We study the response of low-dimensional semiconductor superlattices to strong terahertz fields on condition of a strong suppression of inelastic scattering processes of electrons caused by the polar-optical phonons. For our study we employ a balance equations approach which allows investigating the response of the superlattices to strong terahertz fields taking account of both the inelastic and the strongly pronounced elastic scattering of electrons. Our approach provides a way to analyze the influence of the Bloch dynamics of electrons in a superlattice miniband side by side with the effects of the electron heating on the magnitude and the frequency dependence of a superlattice current responsivity in the terahertz frequency band. Our study shows that the suppression of the inelastic scattering caused either by a reduction of the superlattice dimensionality by lateral quantization or by a strong magnetic field application can give rise to a huge enhancement of the current responsivity. This enhancement can be interpreted in terms of the well pronounced electronic bolometric effect occurring due to the efficient electron heating in the low-dimensional superlattices by the incident terahertz fields.