Knowing the energy levels in quantum dot films is a crucial variable for determining materials to be used for electrodes and other active layers (i.e., hole blocking layer, as well as operation conditions in quantum dot devices. Kelvin Probe Force Microscopy (KPFM), a technique commonly used to determine the contact potential difference between materials, is used to determine the Fermi level position of lead chalcogenide and silver chalcogenide quantum dot films. Choice of capping ligand during film formation is shown to have significant effect on the position of the Fermi level, valence, and conduction bands. In Ag2Se quantum dots films a 0.3 eV variation in Fermi level as a function of capping ligand is observed while 0.45 eV variation is observed in PbSe quantum dot films, with iodide-based ligands showing the highest Fermi level position and oleylamine displaying the lowest. KPFM measurement procedure is outlined, and the current strength and limitations of the technique are discussed.
{"title":"Understanding methods to determine energy levels of quantum dot films for device integration","authors":"Tom Nakotte, Simran Singh, Anna M. Hiszpanksi","doi":"10.1117/12.2631667","DOIUrl":"https://doi.org/10.1117/12.2631667","url":null,"abstract":"Knowing the energy levels in quantum dot films is a crucial variable for determining materials to be used for electrodes and other active layers (i.e., hole blocking layer, as well as operation conditions in quantum dot devices. Kelvin Probe Force Microscopy (KPFM), a technique commonly used to determine the contact potential difference between materials, is used to determine the Fermi level position of lead chalcogenide and silver chalcogenide quantum dot films. Choice of capping ligand during film formation is shown to have significant effect on the position of the Fermi level, valence, and conduction bands. In Ag2Se quantum dots films a 0.3 eV variation in Fermi level as a function of capping ligand is observed while 0.45 eV variation is observed in PbSe quantum dot films, with iodide-based ligands showing the highest Fermi level position and oleylamine displaying the lowest. KPFM measurement procedure is outlined, and the current strength and limitations of the technique are discussed.","PeriodicalId":13820,"journal":{"name":"International Conference on Nanoscience, Engineering and Technology (ICONSET 2011)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85574924","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. Jorio, Cassiano Rabelo, R. Nadas, Hudson Miranda, T. Vasconcelos, B. Archanjo, A. Gadelha, L. G. Cançado
Here we report graphene systems' nano-Raman hyperspectral imaging based on tip-enhanced Raman scattering (TERS). The vibrational and electronic structures are modulated within the graphene-related materials, leading to nano-scale changes in the behavior of electrons and phonons that can be used for spectral imaging. Furthermore, we utilize a He-focused ion beam to do nanolithography on graphene. We then show that the tiny features on graphene made by the He-focused ion beam can only be visualized under nanometer-scaled spectroscopy imaging. We have also imaged low-angle reconstructed twisted bilayer graphene, and our observations highlight the relevance of solitons and topological points for the structures' vibrational and electronic properties, relevant in the context of twistronics.
{"title":"Nano-Raman spectral imaging of localized vibrations in two-dimensional systems","authors":"A. Jorio, Cassiano Rabelo, R. Nadas, Hudson Miranda, T. Vasconcelos, B. Archanjo, A. Gadelha, L. G. Cançado","doi":"10.1117/12.2633265","DOIUrl":"https://doi.org/10.1117/12.2633265","url":null,"abstract":"Here we report graphene systems' nano-Raman hyperspectral imaging based on tip-enhanced Raman scattering (TERS). The vibrational and electronic structures are modulated within the graphene-related materials, leading to nano-scale changes in the behavior of electrons and phonons that can be used for spectral imaging. Furthermore, we utilize a He-focused ion beam to do nanolithography on graphene. We then show that the tiny features on graphene made by the He-focused ion beam can only be visualized under nanometer-scaled spectroscopy imaging. We have also imaged low-angle reconstructed twisted bilayer graphene, and our observations highlight the relevance of solitons and topological points for the structures' vibrational and electronic properties, relevant in the context of twistronics.","PeriodicalId":13820,"journal":{"name":"International Conference on Nanoscience, Engineering and Technology (ICONSET 2011)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85731087","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}
Melisa Ekin Gulseren, L. Domulevicz, J. Hihath, J. S. Gómez-Díaz
Typical surface-enhanced Raman scattering (SERS) approaches rely on localized surface plasmon resonances that provide a significant enhancement of the localized electric field. Unfortunately, this technique faces challenges in terms of repeatability, which appears due to the strong dependence of the field enhancement on the surface roughness and the presence of hot-spots in nanostructures; and adequate excitation, as the laser beam must be tuned at a very specific wavelength that corresponds to the resonant frequency of the system. Hyperbolic metamaterials (HMTMs), a type of composite materials whose effective permittivity changes as a function of the electric field polarization, can effectively address these challenges because they support bulk and surface hyperbolic modes able to drastically boost the local fields over a broadband portion of the electromagnetic spectrum. In fact, the frequency response of these artificial materials can be manipulated by adjusting the system composing materials and filling ratios. This work aims to explore the potential of HMTMs to enhance the SERS of molecules located nearby and to address some of the challenges faced by common SERS platforms. To this purpose, we focus on Au/SiO2 HMTMs stacks that exhibit a hyperbolic dispersion for wavelengths larger than ~580 nm. A prototype has been fabricated and characterized using TEM and ellipsometry measurements. Power-dependent SERS measurements were obtained for a monolayer of biphenyl-4,4’-dithiol (BPDT) molecules self-assembled onto the HMTM surface and a gold-based control sample. HMTMs provide repeatable SERS detection with low laser powers <900µW and integration times <97ms (~30X and ~100X lower than control, respectively) over a large surface area, exhibiting a performance like complex TERS systems.
{"title":"Hyperbolic metamaterials for large-area Surface-Enhanced Raman Scattering (SERS) sensing","authors":"Melisa Ekin Gulseren, L. Domulevicz, J. Hihath, J. S. Gómez-Díaz","doi":"10.1117/12.2633267","DOIUrl":"https://doi.org/10.1117/12.2633267","url":null,"abstract":"Typical surface-enhanced Raman scattering (SERS) approaches rely on localized surface plasmon resonances that provide a significant enhancement of the localized electric field. Unfortunately, this technique faces challenges in terms of repeatability, which appears due to the strong dependence of the field enhancement on the surface roughness and the presence of hot-spots in nanostructures; and adequate excitation, as the laser beam must be tuned at a very specific wavelength that corresponds to the resonant frequency of the system. Hyperbolic metamaterials (HMTMs), a type of composite materials whose effective permittivity changes as a function of the electric field polarization, can effectively address these challenges because they support bulk and surface hyperbolic modes able to drastically boost the local fields over a broadband portion of the electromagnetic spectrum. In fact, the frequency response of these artificial materials can be manipulated by adjusting the system composing materials and filling ratios. This work aims to explore the potential of HMTMs to enhance the SERS of molecules located nearby and to address some of the challenges faced by common SERS platforms. To this purpose, we focus on Au/SiO2 HMTMs stacks that exhibit a hyperbolic dispersion for wavelengths larger than ~580 nm. A prototype has been fabricated and characterized using TEM and ellipsometry measurements. Power-dependent SERS measurements were obtained for a monolayer of biphenyl-4,4’-dithiol (BPDT) molecules self-assembled onto the HMTM surface and a gold-based control sample. HMTMs provide repeatable SERS detection with low laser powers <900µW and integration times <97ms (~30X and ~100X lower than control, respectively) over a large surface area, exhibiting a performance like complex TERS systems.","PeriodicalId":13820,"journal":{"name":"International Conference on Nanoscience, Engineering and Technology (ICONSET 2011)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86084736","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}
An efficient photonic hardware integration of neural networks can benefit us from the inherent properties of parallelism, high-speed data processing and potentially low energy consumption. In artificial neural networks (ANN), neurons are classified as static, single and continuous-valued. On contrary, information transmission and computation in biological neurons occur through spikes, where spike time and rate play a significant role. Spiking neural networks (SNNs) are thereby more biologically relevant along with additional benefits in terms of hardware friendliness and energy-efficiency. Considering all these advantages, we designed a photonic reservoir computer (RC) based on photonic recurrent spiking neural networks (SNN) i.e. a liquid state machine. It is a scalable proof-of-concept experiment, comprising more than 30,000 neurons. This system presents an excellent testbed for demonstrating next generation bio-inspired learning in photonic systems.
{"title":"Realisation of large-scale photonic spiking hardware system","authors":"Ria Talukder, X. Porte, D. Brunner","doi":"10.1117/12.2633530","DOIUrl":"https://doi.org/10.1117/12.2633530","url":null,"abstract":"An efficient photonic hardware integration of neural networks can benefit us from the inherent properties of parallelism, high-speed data processing and potentially low energy consumption. In artificial neural networks (ANN), neurons are classified as static, single and continuous-valued. On contrary, information transmission and computation in biological neurons occur through spikes, where spike time and rate play a significant role. Spiking neural networks (SNNs) are thereby more biologically relevant along with additional benefits in terms of hardware friendliness and energy-efficiency. Considering all these advantages, we designed a photonic reservoir computer (RC) based on photonic recurrent spiking neural networks (SNN) i.e. a liquid state machine. It is a scalable proof-of-concept experiment, comprising more than 30,000 neurons. This system presents an excellent testbed for demonstrating next generation bio-inspired learning in photonic systems.","PeriodicalId":13820,"journal":{"name":"International Conference on Nanoscience, Engineering and Technology (ICONSET 2011)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88048952","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}
Michael J Gleichweit, Mercede A. Mohajer, Dominique Borgeaud, Matus E. Diveky, G. David, R. Signorell
Photoacoustic spectroscopy and photothermal spectroscopy are two common methods to probe aerosol particle absorption coefficients and can be performed both on aerosol ensembles and on the single particle level. With photothermal spectroscopy typically changes in the particle’s light scattering pattern upon heating or cooling are observed with photo-diodes or cameras. In photoacoustic spectroscopy, the acoustic response to periodic light absorption is recorded e.g. with a microphone. Although both methods are closely related through their excitation process, the detection pathways are quintessentially different. In our single particle optical trapping setup, however, we observe a previously unnoticeable, unidirectional coupling between modulated Mie scattering (result of the photothermal effect) and photoacoustic spectroscopy. The coupling manifests itself via differently shaped, sudden features in the acoustic signal. Our analysis suggests a non-trivial interaction between light scattering of single, optically trapped particles and the photoacoustic signal generation based on interactions of light with the acoustic resonator’s walls. Measurements over several trapping powers and photoacoustic excitation powers support this conclusion. How the coupling manifests itself, such as shape and strength, can be conclusively explained by the structure of the particle’s momentary phase function (scattering intensity) calculated by classical Mie theory. This allows us to formulate conditions to either utilise or minimise the coupling effects in future experiments.
{"title":"Coupling between modulated Mie scattering and photoacoustic signal generation in optically trapped, single aerosol particles","authors":"Michael J Gleichweit, Mercede A. Mohajer, Dominique Borgeaud, Matus E. Diveky, G. David, R. Signorell","doi":"10.1117/12.2633423","DOIUrl":"https://doi.org/10.1117/12.2633423","url":null,"abstract":"Photoacoustic spectroscopy and photothermal spectroscopy are two common methods to probe aerosol particle absorption coefficients and can be performed both on aerosol ensembles and on the single particle level. With photothermal spectroscopy typically changes in the particle’s light scattering pattern upon heating or cooling are observed with photo-diodes or cameras. In photoacoustic spectroscopy, the acoustic response to periodic light absorption is recorded e.g. with a microphone. Although both methods are closely related through their excitation process, the detection pathways are quintessentially different. In our single particle optical trapping setup, however, we observe a previously unnoticeable, unidirectional coupling between modulated Mie scattering (result of the photothermal effect) and photoacoustic spectroscopy. The coupling manifests itself via differently shaped, sudden features in the acoustic signal. Our analysis suggests a non-trivial interaction between light scattering of single, optically trapped particles and the photoacoustic signal generation based on interactions of light with the acoustic resonator’s walls. Measurements over several trapping powers and photoacoustic excitation powers support this conclusion. How the coupling manifests itself, such as shape and strength, can be conclusively explained by the structure of the particle’s momentary phase function (scattering intensity) calculated by classical Mie theory. This allows us to formulate conditions to either utilise or minimise the coupling effects in future experiments.","PeriodicalId":13820,"journal":{"name":"International Conference on Nanoscience, Engineering and Technology (ICONSET 2011)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84904831","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}
Xintong Li, Zhida Liu, Yihan Liu, Suyogya Karki, Xiaoqin Li, D. Akinwande, J. Incorvia
The spin and valley physics in 2-dimensional van der Waals materials provides a unique platform for novel applications in spintronics and valleytronics. 2H phase transition metal dichalcogenides (TMD) monolayers possesses broken inversion symmetry and strong spin-orbit coupling, leading to a coupled spin and valley physics that makes them better candidates for these applications. For practical device applications, spin and valley Hall effect (SVHE) is a good way of charge to spin and charge to valley conversion, making the electrical generation of spin and valley polarization possible. While SVHE has been observed via optical measurements at cryotemperatures below 30 K, the behavior at elevated temperatures and thorough understanding of the data are still lacking. In this work we conduct spatial Kerr rotation (KR) measurements on monolayer tungsten diselenide (WSe2) field effect transistors and study the electrical control and temperature dependence of SVHE. We image the distribution of the spin and valley polarization directly and find clear evidence of the spin and valley accumulation at the edges. We show that the SVHE can be electrically modulated by the gate and drain bias, and the polarization persists at elevated temperatures. We then conduct four-port electrical test reflection spectra measurement and use a drift-diffusion model to interpret the data and extract key parameters. A lower-bound spin/valley lifetime is predicted of 40 ns and a mean free path of 240 nm below 90 K. The spin/valley polarization on the edge is calculated to be ~4% at 45 K. WSe2-on-hBN samples are prepared as well, and the KR measurements on these samples are discussed.
{"title":"Controlling spin and valley hall effect in monolayer WSe2 at elevated temperatures","authors":"Xintong Li, Zhida Liu, Yihan Liu, Suyogya Karki, Xiaoqin Li, D. Akinwande, J. Incorvia","doi":"10.1117/12.2633913","DOIUrl":"https://doi.org/10.1117/12.2633913","url":null,"abstract":"The spin and valley physics in 2-dimensional van der Waals materials provides a unique platform for novel applications in spintronics and valleytronics. 2H phase transition metal dichalcogenides (TMD) monolayers possesses broken inversion symmetry and strong spin-orbit coupling, leading to a coupled spin and valley physics that makes them better candidates for these applications. For practical device applications, spin and valley Hall effect (SVHE) is a good way of charge to spin and charge to valley conversion, making the electrical generation of spin and valley polarization possible. While SVHE has been observed via optical measurements at cryotemperatures below 30 K, the behavior at elevated temperatures and thorough understanding of the data are still lacking. In this work we conduct spatial Kerr rotation (KR) measurements on monolayer tungsten diselenide (WSe2) field effect transistors and study the electrical control and temperature dependence of SVHE. We image the distribution of the spin and valley polarization directly and find clear evidence of the spin and valley accumulation at the edges. We show that the SVHE can be electrically modulated by the gate and drain bias, and the polarization persists at elevated temperatures. We then conduct four-port electrical test reflection spectra measurement and use a drift-diffusion model to interpret the data and extract key parameters. A lower-bound spin/valley lifetime is predicted of 40 ns and a mean free path of 240 nm below 90 K. The spin/valley polarization on the edge is calculated to be ~4% at 45 K. WSe2-on-hBN samples are prepared as well, and the KR measurements on these samples are discussed.","PeriodicalId":13820,"journal":{"name":"International Conference on Nanoscience, Engineering and Technology (ICONSET 2011)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73049530","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}
Recently proposed nonvolatile chalcogenide phase change materials Sb2Se3 and Sb2S3 exhibit low loss and significant refractive index modulation in the visible and NIR, which paves the way for the development of novel reconfigurable on-chip nanophotonic devices and programmable optical devices. Here, we discuss our recent investigations in terms of such devices, in particular, the realization of a compact (3 μm × 3 μm) integrated silicon nanophotonic 1 × 2 optical switch with phase change material Sb2Se3, and programmable multilevel diffractive optical lenses and holograms with phase change material Sb2S3.
{"title":"Reconfigurable and programmable optical devices with phase change materials Sb2S3 and Sb2Se3","authors":"W. Jia, R. Menon, B. Sensale‐Rodriguez","doi":"10.1117/12.2633641","DOIUrl":"https://doi.org/10.1117/12.2633641","url":null,"abstract":"Recently proposed nonvolatile chalcogenide phase change materials Sb2Se3 and Sb2S3 exhibit low loss and significant refractive index modulation in the visible and NIR, which paves the way for the development of novel reconfigurable on-chip nanophotonic devices and programmable optical devices. Here, we discuss our recent investigations in terms of such devices, in particular, the realization of a compact (3 μm × 3 μm) integrated silicon nanophotonic 1 × 2 optical switch with phase change material Sb2Se3, and programmable multilevel diffractive optical lenses and holograms with phase change material Sb2S3.","PeriodicalId":13820,"journal":{"name":"International Conference on Nanoscience, Engineering and Technology (ICONSET 2011)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76764098","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}
Rachel E. Gariepy, Xiaojing Xia, R. G. Felsted, Ayelet Teitelbom, E. Chan, P. Pauzauskie
Microlaser designs based on the coupling of whispering gallery modes (WGMs) with the upconversion processes which take place within lanthanide-doped nanoparticles (UCNPs) have been demonstrated and shown to have many valuable qualities, such as high Q factors and low lasing thresholds. One obstacle that these microlaser designs still face is the challenges caused by photothermal heating of the gain medium, which could be solved through the design of a radiation balanced microlaser. In this work, WGM microresonators composed of 5 μm diameter polystyrene spheres are fabricated with a layer of Yb3+-doped NaYF4 UCNPs in order to test if the anti-Stokes cooling properties of the UCNPs can cool the microresonator and its environment under laser irradiation. We find via calibrated mean fluorescence spectroscopy that the UCNPs can cool their local environment by as much as 23 °C and significantly reduce the heating of the aqueous environment surrounding the microresonator, showing promise for inclusion in a design for a radiation balanced microlaser.
{"title":"Solid-state laser refrigeration of core-shell polystyrene microspheres","authors":"Rachel E. Gariepy, Xiaojing Xia, R. G. Felsted, Ayelet Teitelbom, E. Chan, P. Pauzauskie","doi":"10.1117/12.2635908","DOIUrl":"https://doi.org/10.1117/12.2635908","url":null,"abstract":"Microlaser designs based on the coupling of whispering gallery modes (WGMs) with the upconversion processes which take place within lanthanide-doped nanoparticles (UCNPs) have been demonstrated and shown to have many valuable qualities, such as high Q factors and low lasing thresholds. One obstacle that these microlaser designs still face is the challenges caused by photothermal heating of the gain medium, which could be solved through the design of a radiation balanced microlaser. In this work, WGM microresonators composed of 5 μm diameter polystyrene spheres are fabricated with a layer of Yb3+-doped NaYF4 UCNPs in order to test if the anti-Stokes cooling properties of the UCNPs can cool the microresonator and its environment under laser irradiation. We find via calibrated mean fluorescence spectroscopy that the UCNPs can cool their local environment by as much as 23 °C and significantly reduce the heating of the aqueous environment surrounding the microresonator, showing promise for inclusion in a design for a radiation balanced microlaser.","PeriodicalId":13820,"journal":{"name":"International Conference on Nanoscience, Engineering and Technology (ICONSET 2011)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74536823","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}
Van Doan Le, Balint Eles, N. Dalloz, Manuel A. Flores Figueroa, F. Vocanson, Y. Lefkir, N. Destouches
Laser can be an effective tool to modify materials at the nanoscale in order to achieve desired optical properties. When dealing with metal-dielectric nanocomposite thin films, different mechanisms can be triggered by laser on large areas to control the statistical properties of these materials. Nanoparticles can be reshaped, resized and ordered according to self-organization mechanisms that set over micrometer wide areas. The dielectric crystal phase and film thickness can be changed upon laser-induced temperature rise. These mechanisms lead to changes in the optical properties of the films. Here, we investigate the structural changes that a Ag:TiO2 nanocomposite thin film undergoes under nanosecond laser scanning and their resulting optical properties. We especially focus on the color properties in different modes of observation such as reflection and diffraction. The colors originate from combination of absorption by the localized surface plasmon resonance of metallic nanoparticles, diffraction by the nanoparticles assemblies and interference between the incident, reflected and guided waves, the latter being excited by scattering on the nanoparticles. The morphological characterizations unveil the role of nanoparticle size, density and arrangement on the transition from a diffractive to a dichroic behavior. A full color image is also drawn to demonstrate the potential of the technique in industrial applications ranging from design, coloration to information storage and data security.
{"title":"Direct color printing on Ag:TiO2 thin films induced by nanosecond laser pulses","authors":"Van Doan Le, Balint Eles, N. Dalloz, Manuel A. Flores Figueroa, F. Vocanson, Y. Lefkir, N. Destouches","doi":"10.1117/12.2632435","DOIUrl":"https://doi.org/10.1117/12.2632435","url":null,"abstract":"Laser can be an effective tool to modify materials at the nanoscale in order to achieve desired optical properties. When dealing with metal-dielectric nanocomposite thin films, different mechanisms can be triggered by laser on large areas to control the statistical properties of these materials. Nanoparticles can be reshaped, resized and ordered according to self-organization mechanisms that set over micrometer wide areas. The dielectric crystal phase and film thickness can be changed upon laser-induced temperature rise. These mechanisms lead to changes in the optical properties of the films. Here, we investigate the structural changes that a Ag:TiO2 nanocomposite thin film undergoes under nanosecond laser scanning and their resulting optical properties. We especially focus on the color properties in different modes of observation such as reflection and diffraction. The colors originate from combination of absorption by the localized surface plasmon resonance of metallic nanoparticles, diffraction by the nanoparticles assemblies and interference between the incident, reflected and guided waves, the latter being excited by scattering on the nanoparticles. The morphological characterizations unveil the role of nanoparticle size, density and arrangement on the transition from a diffractive to a dichroic behavior. A full color image is also drawn to demonstrate the potential of the technique in industrial applications ranging from design, coloration to information storage and data security.","PeriodicalId":13820,"journal":{"name":"International Conference on Nanoscience, Engineering and Technology (ICONSET 2011)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83497580","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}
Monolayers of transition metal dichalcogenides (TMDCs) have caught the interest of post-silicon electronics and optoelectronics researchers due to their exceptional electronic and optoelectronic properties which stem from their unique two-dimensional (2D) layered structure. In recent years, there has been a focus on exploring van der Waals (vdW) heterojunctions with TMDCs, including with lower dimensionality materials such as zero-dimensional (0D) systems. Integrating 0D-2D assemblies together provides an opportunity to configure a diverse array of material stacks towards optoelectronics and electronics applications. In this study, we synthesized 0D-2D vdW heterostructure by spin coating C60 molecules on halide-assisted-low-pressure chemical-vapor-deposition (HA-LPCVD) produced monolayer WSe2 flakes. Raman and photoluminescence spectroscopy allowed us to assess the charge carrier exchange at the vdW interface. We found that after C60 deposition, the photodetector figures of merit for WSe2 − C60 hybrids improved, and investigations were conducted as a function of illumination power. Our studies reveal that WSe2 − C60 hybrid system is an appealing choice for next generation optical sensing devices.
{"title":"Photoexcitation of C60-WSe2 hybrids for optical sensing","authors":"K. Jayanand, Silvino P. Bastos, A. Kaul","doi":"10.1117/12.2632594","DOIUrl":"https://doi.org/10.1117/12.2632594","url":null,"abstract":"Monolayers of transition metal dichalcogenides (TMDCs) have caught the interest of post-silicon electronics and optoelectronics researchers due to their exceptional electronic and optoelectronic properties which stem from their unique two-dimensional (2D) layered structure. In recent years, there has been a focus on exploring van der Waals (vdW) heterojunctions with TMDCs, including with lower dimensionality materials such as zero-dimensional (0D) systems. Integrating 0D-2D assemblies together provides an opportunity to configure a diverse array of material stacks towards optoelectronics and electronics applications. In this study, we synthesized 0D-2D vdW heterostructure by spin coating C60 molecules on halide-assisted-low-pressure chemical-vapor-deposition (HA-LPCVD) produced monolayer WSe2 flakes. Raman and photoluminescence spectroscopy allowed us to assess the charge carrier exchange at the vdW interface. We found that after C60 deposition, the photodetector figures of merit for WSe2 − C60 hybrids improved, and investigations were conducted as a function of illumination power. Our studies reveal that WSe2 − C60 hybrid system is an appealing choice for next generation optical sensing devices.","PeriodicalId":13820,"journal":{"name":"International Conference on Nanoscience, Engineering and Technology (ICONSET 2011)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87857890","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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