Photocurrents in bulk tellurium

TL;DR

This paper presents a detailed experimental and theoretical analysis of various polarization-dependent photocurrents in bulk tellurium, revealing new effects and their origins at different frequencies.

Contribution

It introduces the first comprehensive study of multiple photocurrent effects in tellurium, supported by phenomenological and microscopic theories, distinguishing effects by polarization, magnetic field, and frequency.

Findings

New photocurrent effects observed in tellurium.

Photocurrents caused by different mechanisms at THz and infrared frequencies.

Theoretical models successfully explain experimental results.

Abstract

We report a comprehensive study of polarized infrared/terahertz photocurrents in bulk tellurium crystals. We observe different photocurrent contributions and show that, depending on the experimental conditions, they are caused by the trigonal photogalvanic effect, the transverse linear photon drag effect, and the magnetic field induced linear and circular photogalvanic effects. All observed photocurrents have not been reported before and are well explained by the developed phenomenological and microscopic theory. We show that the effects can be unambiguously distinguished by studying the polarization, magnetic field, and radiation frequency dependence of the photocurrent. At frequencies around 30 THz, the photocurrents are shown to be caused by the direct optical transitions between subbands in the valence band. At lower frequencies of 1 to 3 THz, used in our experiment, these transitions become impossible and the detected photocurrents are caused by the indirect optical transitions (Drude-like radiation absorption).