The terahertz (THz) wave generation by photoconductive antennas fabricated on the low-temperature and high- temperature grown In0.5Ga0.5As semiconductor and Bi2-xSbxTe3-ySey (BSTS) topological insulator films is studied by the terahertz time-domain spectroscopy method. THz generation property of In0.5Ga0.5As layers grown by molecular beam epitaxy on GaAs substrates with (100) and (111)A crystallographic orientations is compared with THz generation capability of the BSTS films grown by the MOCVD method on a sapphire substrate. Antennas of the both types were excited by radiation of Er3+ -fiber laser at 1.56 um wavelength. THz generation by InGaAs-based antennas on (111)A GaAs substrates was 3–4 times more effective than the same antennas fabricated on the (100) wafers. It was found that the generation of THz waves was more efficient in an island film of BSTS having a total thickness of about tens nanometers with that chemical composition where the volume contribution to conductivity was suppressed. Strong amplification of the THz radiation power has been demonstrated after applying an external electric field to the topological insulator film.
{"title":"Generation of terahertz radiation in antennas based on epitaxial films of semiconductors and topological insulators","authors":"K. Kuznetsov, P. Kuznetsov, G. Galiev, G. Kitaeva","doi":"10.1063/5.0054924","DOIUrl":"https://doi.org/10.1063/5.0054924","url":null,"abstract":"The terahertz (THz) wave generation by photoconductive antennas fabricated on the low-temperature and high- temperature grown In0.5Ga0.5As semiconductor and Bi2-xSbxTe3-ySey (BSTS) topological insulator films is studied by the terahertz time-domain spectroscopy method. THz generation property of In0.5Ga0.5As layers grown by molecular beam epitaxy on GaAs substrates with (100) and (111)A crystallographic orientations is compared with THz generation capability of the BSTS films grown by the MOCVD method on a sapphire substrate. Antennas of the both types were excited by radiation of Er3+ -fiber laser at 1.56 um wavelength. THz generation by InGaAs-based antennas on (111)A GaAs substrates was 3–4 times more effective than the same antennas fabricated on the (100) wafers. It was found that the generation of THz waves was more efficient in an island film of BSTS having a total thickness of about tens nanometers with that chemical composition where the volume contribution to conductivity was suppressed. Strong amplification of the THz radiation power has been demonstrated after applying an external electric field to the topological insulator film.","PeriodicalId":405600,"journal":{"name":"PROCEEDINGS OF INTERNATIONAL CONGRESS ON GRAPHENE, 2D MATERIALS AND APPLICATIONS (2D MATERIALS 2019)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122864149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Fateev, I. M. Moiseenko, K. Mashinsky, V. Popov
We demonstrate that the periodic graphene structure with asymmetric unit cell can effectively transform the incident electromagnetic wave into propagating plasmon. Periodic graphene structure with asymmetric unit cell and active graphene transforms the incident electromagnetic wave into amplifying propagating plasmon.
{"title":"Conversion of electromagnetic wave into propagating plasmon in a periodic graphene structure","authors":"D. Fateev, I. M. Moiseenko, K. Mashinsky, V. Popov","doi":"10.1063/5.0054952","DOIUrl":"https://doi.org/10.1063/5.0054952","url":null,"abstract":"We demonstrate that the periodic graphene structure with asymmetric unit cell can effectively transform the incident electromagnetic wave into propagating plasmon. Periodic graphene structure with asymmetric unit cell and active graphene transforms the incident electromagnetic wave into amplifying propagating plasmon.","PeriodicalId":405600,"journal":{"name":"PROCEEDINGS OF INTERNATIONAL CONGRESS ON GRAPHENE, 2D MATERIALS AND APPLICATIONS (2D MATERIALS 2019)","volume":"54 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127659458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We report terahertz photoconductivity in epitaxial graphene devices patterned in a meander shape with the length up to a few centimeters and the width of few tens of microns. The photoresponse signal was measured at wavelengths of 280, 148 and 90 microns (frequencies 1, 2. and 3.3 THz) as a function of the electron concentration, bias current, terahertz radiation intensity and magnetic field. The photoconductivity mechanism based on the model of electron heating by terahertz radiation well explains the experimental results.
{"title":"Terahertz photoresponse of meander-patterned graphene","authors":"Y. Vasilyev, S. Novikov","doi":"10.1063/5.0054940","DOIUrl":"https://doi.org/10.1063/5.0054940","url":null,"abstract":"We report terahertz photoconductivity in epitaxial graphene devices patterned in a meander shape with the length up to a few centimeters and the width of few tens of microns. The photoresponse signal was measured at wavelengths of 280, 148 and 90 microns (frequencies 1, 2. and 3.3 THz) as a function of the electron concentration, bias current, terahertz radiation intensity and magnetic field. The photoconductivity mechanism based on the model of electron heating by terahertz radiation well explains the experimental results.","PeriodicalId":405600,"journal":{"name":"PROCEEDINGS OF INTERNATIONAL CONGRESS ON GRAPHENE, 2D MATERIALS AND APPLICATIONS (2D MATERIALS 2019)","volume":"138 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132374890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dynamics of the magneto-optical Kerr effect in a multilayer TbCo2 / FeCo metal structure consisting of alternating layers 1.5 nm thick was studied in this work. The relaxation process was considered over a time interval of up to 170 ps using the femtosecond pump-probe spectroscopy. The experiment was carried out in 2 geometries, when the external field was along the “easy” axis and along the “heavy” axis. The maximum value of the applied magnetic field along the «easy axis» was 4.5 kOe, and along the «heavy» axis 5 kOe. Based on the approximation of the dynamics of the Kerr effect, the dependences of the oscillation frequency, amplitude and decay time are obtained. It is shown that in the geometry of the “heavy axis”, in contrast to the geometry of the “easy axis”, the amplitude of the oscillations is several times larger, and the decay of the precession is several times slower. The dependence of the amplitude of oscillations in the “heavy axis” geometry has a maximum at an external field of about 2 kOe, the value of which is close to the saturation field along this axis.
{"title":"Ultrafast dynamics of the magneto-optical Kerr effect in multilayer TbCo/FeCo structures under the influence of femtosecond optical excitation","authors":"M. Gaponov, S. Ovcharenko, N. Ilyin","doi":"10.1063/5.0054910","DOIUrl":"https://doi.org/10.1063/5.0054910","url":null,"abstract":"Dynamics of the magneto-optical Kerr effect in a multilayer TbCo2 / FeCo metal structure consisting of alternating layers 1.5 nm thick was studied in this work. The relaxation process was considered over a time interval of up to 170 ps using the femtosecond pump-probe spectroscopy. The experiment was carried out in 2 geometries, when the external field was along the “easy” axis and along the “heavy” axis. The maximum value of the applied magnetic field along the «easy axis» was 4.5 kOe, and along the «heavy» axis 5 kOe. Based on the approximation of the dynamics of the Kerr effect, the dependences of the oscillation frequency, amplitude and decay time are obtained. It is shown that in the geometry of the “heavy axis”, in contrast to the geometry of the “easy axis”, the amplitude of the oscillations is several times larger, and the decay of the precession is several times slower. The dependence of the amplitude of oscillations in the “heavy axis” geometry has a maximum at an external field of about 2 kOe, the value of which is close to the saturation field along this axis.","PeriodicalId":405600,"journal":{"name":"PROCEEDINGS OF INTERNATIONAL CONGRESS ON GRAPHENE, 2D MATERIALS AND APPLICATIONS (2D MATERIALS 2019)","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114791499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Khusyainov, A. Gorbatova, A. Buryakov, E. Mishina
Surface THz emission was observed from monolayer and bulk WSe2 via THz time-domain spectroscopy. Frequency and temporal spectra of the generated THz pulses were studied. Azimuthal dependencies of peak-to-peak THz amplitude were obtained for both layered WSe2. It was assumed that the generation of THz radiation in the bulk WSe2 occur due to the motion of photoexcited carriers and in the monolayer WSe2 due to nonlinear processes occurring after interaction with optical femtosecond pulses.
{"title":"THz surface emission from bulk and monolayer WSe2","authors":"D. Khusyainov, A. Gorbatova, A. Buryakov, E. Mishina","doi":"10.1063/5.0055455","DOIUrl":"https://doi.org/10.1063/5.0055455","url":null,"abstract":"Surface THz emission was observed from monolayer and bulk WSe2 via THz time-domain spectroscopy. Frequency and temporal spectra of the generated THz pulses were studied. Azimuthal dependencies of peak-to-peak THz amplitude were obtained for both layered WSe2. It was assumed that the generation of THz radiation in the bulk WSe2 occur due to the motion of photoexcited carriers and in the monolayer WSe2 due to nonlinear processes occurring after interaction with optical femtosecond pulses.","PeriodicalId":405600,"journal":{"name":"PROCEEDINGS OF INTERNATIONAL CONGRESS ON GRAPHENE, 2D MATERIALS AND APPLICATIONS (2D MATERIALS 2019)","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131762914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Preface: International Congress on Graphene, 2D Materials and Applications 2D Materials 2019","authors":"VolkovValentyn, NikitinAlexey, V. ArseninAleksey","doi":"10.1063/12.0004940","DOIUrl":"https://doi.org/10.1063/12.0004940","url":null,"abstract":"","PeriodicalId":405600,"journal":{"name":"PROCEEDINGS OF INTERNATIONAL CONGRESS ON GRAPHENE, 2D MATERIALS AND APPLICATIONS (2D MATERIALS 2019)","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125054149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Polyakov, L. Yadgarov, V. Lebedev, R. Chumakov, L. Yashina, M. Rumyantseva, R. Tenne, E. Goodilin
This conference contribution is focused on decoration of WS2 nanotubes (NT-WS2) with gold and silver nanoparticles via facile routes implying direct reaction of tungsten disulfide with water-soluble AuIII and AgI species at 100°C. The underlying mechanism of these interactions will be discussed in details based on extensive studies of reaction mixtures and resulting metal–NT-WS2 nanocomposites, including thorough X-ray photoelectron spectroscopy (XPS) analysis. Surprising features in optical spectra of the designed nanocomposites would be reported, including suppression of plasmon resonance in tiny noble metal nanoparticles (< 10 nm in diameter) grown onto NT-WS2. The plasmonic features of individual gold nanoparticles on the surface of disulfide nanotube were also characterized by electron energy loss spectroscopy in scanning transmission electron microscopy mode (STEM-EELS). Photoresistive NO2−sensing response of NT-WS2 under green light illumination (λmax = 530 nm) and its enhancement by plasmonic gold “nanoantennas” will be reported as well.
本次会议的贡献集中在用金和银纳米粒子修饰WS2纳米管(NT-WS2)上，这意味着在100°C下，二硫化钨与水溶性AuIII和AgI直接反应。这些相互作用的潜在机制将基于对反应混合物和产生的金属- nt - ws2纳米复合材料的广泛研究，包括彻底的x射线光电子能谱(XPS)分析，详细讨论。所设计的纳米复合材料在光谱上的惊人特征将被报道，包括在NT-WS2上生长的微小贵金属纳米颗粒(直径< 10 nm)的等离子体共振被抑制。利用扫描透射电子显微镜(STEM-EELS)对二硫化纳米管表面单个金纳米粒子的等离子体特征进行了表征。本文还将报道NT-WS2在绿光(λmax = 530 nm)照射下的光敏NO2−响应及其等离子体金“纳米天线”的增强。
{"title":"WS2 nanotubes dressed in gold and silver: Synthesis, optoelectronic properties, and NO2 sensing","authors":"A. Polyakov, L. Yadgarov, V. Lebedev, R. Chumakov, L. Yashina, M. Rumyantseva, R. Tenne, E. Goodilin","doi":"10.1063/5.0055823","DOIUrl":"https://doi.org/10.1063/5.0055823","url":null,"abstract":"This conference contribution is focused on decoration of WS2 nanotubes (NT-WS2) with gold and silver nanoparticles via facile routes implying direct reaction of tungsten disulfide with water-soluble AuIII and AgI species at 100°C. The underlying mechanism of these interactions will be discussed in details based on extensive studies of reaction mixtures and resulting metal–NT-WS2 nanocomposites, including thorough X-ray photoelectron spectroscopy (XPS) analysis. Surprising features in optical spectra of the designed nanocomposites would be reported, including suppression of plasmon resonance in tiny noble metal nanoparticles (< 10 nm in diameter) grown onto NT-WS2. The plasmonic features of individual gold nanoparticles on the surface of disulfide nanotube were also characterized by electron energy loss spectroscopy in scanning transmission electron microscopy mode (STEM-EELS). Photoresistive NO2−sensing response of NT-WS2 under green light illumination (λmax = 530 nm) and its enhancement by plasmonic gold “nanoantennas” will be reported as well.","PeriodicalId":405600,"journal":{"name":"PROCEEDINGS OF INTERNATIONAL CONGRESS ON GRAPHENE, 2D MATERIALS AND APPLICATIONS (2D MATERIALS 2019)","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126744066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. Dorofeev, V. Suslyaev, S. Moseenkov, V. Kuznetsov, K. Dorozhkin
The paper presents the modeling of the reflectance in the terahertz range from the plane-parallel aerogel layers formed by multi-walled carbon nanotubes (MWCNTs), which were synthesized via the original one-step technique using a preformed Fe–Co/CaO catalyst at 650–700°C in C2H4/Ar feedstock. With an increase in frequency from 100 GHz to 1.5 THz, the reflectance decreases by more than a factor of two. Based on the experimental data and the well-known wire medium model formed by a three-dimensional lattice of intersecting conductors, a model of a regular wire medium is constructed using MWCNTs with effective electrophysical characteristics equivalent to those of an irregular aerogel medium. This model reveals that a significant drop in the reflectance in the terahertz frequency range occurs because the plasma frequency of the equivalent medium is located here. The model allows estimating the properties of the aerogel environment in the frequency range extending up to 5 THz and with variations in the packing density of MWCNTs in aerogel. Estimates of the reflection, transmission, and absorption are presented for the case of normal EMI incidence on thin (submillimeter) layers of such a medium.
{"title":"Multi-walled carbon nanotube aerogels in quasi-optical terahertz beams","authors":"I. Dorofeev, V. Suslyaev, S. Moseenkov, V. Kuznetsov, K. Dorozhkin","doi":"10.1063/5.0055770","DOIUrl":"https://doi.org/10.1063/5.0055770","url":null,"abstract":"The paper presents the modeling of the reflectance in the terahertz range from the plane-parallel aerogel layers formed by multi-walled carbon nanotubes (MWCNTs), which were synthesized via the original one-step technique using a preformed Fe–Co/CaO catalyst at 650–700°C in C2H4/Ar feedstock. With an increase in frequency from 100 GHz to 1.5 THz, the reflectance decreases by more than a factor of two. Based on the experimental data and the well-known wire medium model formed by a three-dimensional lattice of intersecting conductors, a model of a regular wire medium is constructed using MWCNTs with effective electrophysical characteristics equivalent to those of an irregular aerogel medium. This model reveals that a significant drop in the reflectance in the terahertz frequency range occurs because the plasma frequency of the equivalent medium is located here. The model allows estimating the properties of the aerogel environment in the frequency range extending up to 5 THz and with variations in the packing density of MWCNTs in aerogel. Estimates of the reflection, transmission, and absorption are presented for the case of normal EMI incidence on thin (submillimeter) layers of such a medium.","PeriodicalId":405600,"journal":{"name":"PROCEEDINGS OF INTERNATIONAL CONGRESS ON GRAPHENE, 2D MATERIALS AND APPLICATIONS (2D MATERIALS 2019)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127348840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Ermolaev, D. Yakubovsky, Y. Stebunov, A. A. Voronov, A. Arsenin, V. Volkov
In the present study, we report on dispersion function over a spectral range of 300 – 1700 nm (i.e. 0.73 – 4.13eV) for CVD-grown full area coverage monolayer WS2 and WSe2 films on SiO2/Si substrates. The result is obtained via the analysis of spectroscopic ellipsometry spectra by virtue of Tauc-Lorentz oscillators, which takes into account that absorption of these materials are attributed to the formation of the excitons.
{"title":"Spectroscopic ellipsometry of large area monolayer WS2 and WSe2 films","authors":"G. Ermolaev, D. Yakubovsky, Y. Stebunov, A. A. Voronov, A. Arsenin, V. Volkov","doi":"10.1063/5.0054947","DOIUrl":"https://doi.org/10.1063/5.0054947","url":null,"abstract":"In the present study, we report on dispersion function over a spectral range of 300 – 1700 nm (i.e. 0.73 – 4.13eV) for CVD-grown full area coverage monolayer WS2 and WSe2 films on SiO2/Si substrates. The result is obtained via the analysis of spectroscopic ellipsometry spectra by virtue of Tauc-Lorentz oscillators, which takes into account that absorption of these materials are attributed to the formation of the excitons.","PeriodicalId":405600,"journal":{"name":"PROCEEDINGS OF INTERNATIONAL CONGRESS ON GRAPHENE, 2D MATERIALS AND APPLICATIONS (2D MATERIALS 2019)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117196159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Vasina, A. Y. Avdihziyan, A. Shestakova, S. Lavrov, E. Mishina
In this paper, phototransistors based on a complex alloys Mo0.5W0.5SSe TMDC has been developed and studied. The output and transient characteristics of this transistors were obtained, and the dependence of the operation of such transistors on different wavelengths and power of optical radiation was also received.
{"title":"Optical properties of phototransistors based on complex alloys of transition metal dichalcogenides Mo0.5W0.5SSe","authors":"M. Vasina, A. Y. Avdihziyan, A. Shestakova, S. Lavrov, E. Mishina","doi":"10.1063/5.0057531","DOIUrl":"https://doi.org/10.1063/5.0057531","url":null,"abstract":"In this paper, phototransistors based on a complex alloys Mo0.5W0.5SSe TMDC has been developed and studied. The output and transient characteristics of this transistors were obtained, and the dependence of the operation of such transistors on different wavelengths and power of optical radiation was also received.","PeriodicalId":405600,"journal":{"name":"PROCEEDINGS OF INTERNATIONAL CONGRESS ON GRAPHENE, 2D MATERIALS AND APPLICATIONS (2D MATERIALS 2019)","volume":"3 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120971756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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