Effect Of Weak Magnetic Field ($\sim $\,300 Gs) On the Intensity of Terahertz Emission of Hot Electrons in $n$-Ge at Helium Temperatures

TL;DR

This study investigates how a weak magnetic field around 300 Gs significantly reduces terahertz emission from hot electrons in n-type germanium at helium temperatures, revealing effects on carrier concentration and magnetoresistance.

Contribution

It provides experimental insights into the impact of weak magnetic fields on terahertz emission and electron dynamics in n-Ge at cryogenic temperatures, highlighting anisotropic effects.

Findings

Magnetic field decreases emission intensity by 500-1000%.

Carrier concentration decreases at weak electric fields.

Significant longitudinal magnetoresistance due to anisotropic energy dispersion.

Abstract

Experimental results of studying the effect of a weak magnetic field ($\sim $300 Gs) on the intensity of the terahertz emission ($\lambda \approx $100 $\mu $m) of hot electrons in $n$-Ge (crystallographic orientation $< 1,0,0 >)$ at helium temperatures ($T\sim $5 K) are presented and discussed. It is shown that the strong influence of this field (decrease of the emission intensity by 500$\div $1000{%}) is related to a decrease of the carrier concentration at weak electric fields and the appearance of the magnetoresistance at stronger fields. The longitudinal magnetoresistance becomes significant due to the anisotropy of the energy dispersion law of electrons and a strong deformation of the electron velocity distribution function by the electric field (which is beyond the framework of the diffusion approximation).