Absorption of Terahertz Radiation in Ge/Si(001) Heterostructures with Quantum Dots

TL;DR

This study measures terahertz spectra of Ge/Si(001) heterostructures with quantum dots, revealing significantly enhanced absorption and conductivity compared to bulk Ge, and discusses possible microscopic mechanisms.

Contribution

First measurement of terahertz spectra in Ge/Si heterostructures with quantum dots, showing increased absorption and conductivity due to quantum dot arrays.

Findings

Effective conductivity and absorption are much larger than in bulk Ge.

Quantum dots significantly enhance terahertz absorption.

Microscopic mechanisms of increased absorption are discussed.

Abstract

The terahertz spectra of the dynamic conductivity and radiation absorption coefficient in germanium-silicon heterostructures with arrays of Ge hut clusters (quantum dots) have been measured for the first time in the frequency range of 0.3-1.2 THz at room temperature. It has been found that the effective dynamic conductivity and effective radiation absorption coefficient in the heterostructure due to the presence of germanium quantum dots in it are much larger than the respective quantities of both the bulk Ge single crystal and Ge/Si(001) without arrays of quantum dots. The possible microscopic mechanisms of the detected increase in the absorption in arrays of quantum dots have been discussed.