Enhanced Terahertz Radiation Generation of Photoconductive Antennas Based on Manganese Ferrite Nanoparticles

Abstract

This paper presents a significant effect of manganese ferrite nanoparticles (MnFe2O4 NPs) on the increase of the surface photoconductivity of semiconductors. Herein, the optical characterization of photo-excited carriers of silicon coated with MnFe2O4 NPs was studied by using THz time-domain spectroscopy (THz-TDs). We observed that silicon coated with MnFe2O4 NPs provided a significantly enhanced attenuation of THz radiation in comparison with bare silicon substrates under laser irradiation. The experimental results were assessed in the context of a surface band structure model of semiconductors. In addition, photoconductive antennas coated with MnFe2O4 NPs significantly improved the efficiency of THz radiation generation and signal to noise ratio of the THz signal. This work demonstrates that coating with MnFe2O4 NPs could improve the overall performance of THz systems, and MnFe2O4 NPs could be further used for the implementation of novel optical devices.

Enhanced All-Optical Modulation of Terahertz Waves on the Basis of Manganese Ferrite Nanoparticles

“…Substrates of silicon coated with MnFe 2 O 4 NPs (NPs@Si) were designed by casting one layer of hydrophobic MnFe 2 O 4 NPs on the high-resistivity silicon by the spin-coating process, as described previously (the fabrication details are shown in Methods), and the SEM image of NPs@Si in Figure c exhibits a uniform layer of NPs on the silicon substrate. To analyze the effect of MnFe 2 O 4 NPs on the substrate, optical properties of NPs@Si substrate and bare silicon substrate (Si) were measured under CW laser irradiation (continuous wave (CW), λ ex : 808 nm).…”

“…The NPs@Si system was prepared by coating of monodisperse MnFe 2 O 4 NPs on a silicon substrate by a spin-coating process, as described previously . In detail, a silicon substrate was prewashed by acetone solution with sonication three times, 50 μL of MnFe 2 O 4 NPs solution obtained as already mentioned was dropped on the substrate surface, and the followed rotation (100 rpm, 10 s) was applied to cast a layer of MnFe 2 O 4 NPs on the substrate to fabricate the NPs@Si system.…”

Investigation of the Viability of Cells upon Co-Exposure to Gold and Iron Oxide Nanoparticles

“…Au NPs, Au seed NPs, FeO x NPs, and hybrid Au-FeO x NPs were synthesized in organic solvents according to published protocols. ,− UV–vis absorption spectra of the four NP samples as dissolved in chloroform (CHCl 3 ) were recorded by a Varian Cary 50 spectrophotometer and the core size d c of the NPs was measured with transmission electron microscopy (TEM) . The NPs were transferred to aqueous solution by overcoating them with an amphiphilic polymer poly­(isobutylene- alt -maleic anhydride)- graft -dodecyl, as described in the literature .…”

“…13,29−31 UV−vis absorption spectra of the four NP samples as dissolved in chloroform (CHCl 3 ) were recorded by a Varian Cary 50 spectrophotometer and the core size d c of the NPs was measured with transmission electron microscopy (TEM). 32 The NPs were transferred to aqueous solution by overcoating them with an amphiphilic polymer poly-(isobutylene-alt-maleic anhydride)-graf t-dodecyl, as described in the literature. 33 The hydrodynamic diameters d h and zeta potentials ζ of the NPs dispersed in H 2 O were recorded with a Malvern Zetasizer.…”

Design of a Liquid-Crystal-Tunable Terahertz Demultiplexer Based on a Metal-Insulator-Metal Waveguide

“…Graphene is widely used in adjustable devices owing to the diversity of its tunable parameters [6][7][8]. With adjustable permeability by magnetic fields, ferrite is also attractive for devices in the terahertz or optical range [9][10][11]. Since the liquid crystal (LC) is fluid, it is better used for volume devices, like waveguides [12], or flexible components, like wearable filters [13].…”