Enhancement of Terahertz Radiation by Surface Plasmons Based on CdTe Thin Films.

Huiyan Kong,Heping Zeng,Min Li,Luyi Huang,Ling Zhang

doi:10.3390/nano12020290

Abstract

Terahertz (THz) time-domain spectroscopy (TDS) is a powerful tool used to characterize the surface/interface of materials, and semiconductor/metal interfaces can generate THz emission through ultrafast optical excitation, which can be further improved through the optical excitation of surface plasmons. Here, we assembled cadmium telluride (CdTe) on an AuAg alloy (Au25Ag75, wt.%) substrate and obtained five times stronger THz emission compared with silicon substrate, and found that the enhancement can be tuned by controlling the thickness of the semiconductor materials and plasmonic metal substrates. We believe that our results not only promote the development of THz emission enhancement, but also provide a straightforward way of producing small, thin, and more efficient terahertz photonic devices.

Highlights

Terahertz (THz) technology possesses the unique properties of low energy, a lack of damage, and the unique fingerprint characteristics of non-polar molecules
The 141 cm−1 peak resulted in a combination of TO and E phonon modes of Cd, and the peak at 122 cm−1 was related to the A1 mode of Te in cadmium telluride (CdTe)
The results indicated that noble metal can enhance the THz radiation of CdTe because the electrons in the metal were excited by the laser beam, and accumulated to form surface plasmon polaritons (SPPs) [23]

Summary

Introduction

Terahertz (THz) technology possesses the unique properties of low energy, a lack of damage, and the unique fingerprint characteristics of non-polar molecules It has blossomed rapidly through the development of ultrafast optical technologies and hybrid materials, and has been applied in various fields [1,2,3,4,5,6], such as biological imaging, medical diagnosis, customs security, and high-speed communication. There is an increasing demand for high-efficiency THz emission sources and high-sensitivity THz wave detectors Semiconductor materials, such as layered centrosymmetric 2H-MoS2 (TMDs), InAs, graphene, and Ge crystals, feature high carrier mobility, wide band range, high current on/off and other photoelectric properties, and have been used as sources of electromagnetic radiation in the THz range [7,8,9,10,11].

Methods

Results

Conclusion