SPIE NanoScience + Engineering最新文献_第9页

Ordering and thermal excitations in dipolar coupled single domain magnet arrays (Presentation Recording) 偶极耦合单畴磁体阵列的有序和热激发(演讲录音)

SPIE NanoScience + Engineering Pub Date : 2015-10-05 DOI: 10.1117/12.2188028

E. Östman, U. Arnalds, V. Kapaklis, B. Hjörvarsson

{"title":"Ordering and thermal excitations in dipolar coupled single domain magnet arrays (Presentation Recording)","authors":"E. Östman, U. Arnalds, V. Kapaklis, B. Hjörvarsson","doi":"10.1117/12.2188028","DOIUrl":"https://doi.org/10.1117/12.2188028","url":null,"abstract":"For a small island of a magnetic material the magnetic state of the island is mainly determined by the exchange interaction and the shape anisotropy. Two or more islands placed in close proximity will interact through dipolar interactions. The state of a large system will thus be dictated by interactions at both these length scales. Enabling internal thermal fluctuations, e.g. by the choice of material, of the individual islands allows for the study of thermal ordering in extended nano-patterned magnetic arrays [1,2]. As a result nano-magnetic arrays represent an ideal playground for the study of physical model systems. Here we present three different studies all having used magneto-optical imaging techniques to observe, in real space, the order of the systems. The first study is done on a square lattice of circular islands. The remanent magnetic state of each island is a magnetic vortex structure and we can study the temperature dependence of the vortex nucleation and annihilation fields [3]. The second are long chains of dipolar coupled elongated islands where the magnetization direction in each island only can point in one of two possible directions. This creates a system which in many ways mimics the Ising model [4] and we can relate the correlation length to the temperature. The third one is a spin ice system where elongated islands are placed in a square lattice. Thermal excitations in such systems resemble magnetic monopoles [2] and we can investigate their properties as a function of temperature and lattice parameters. [1] V. Kapaklis et al., New J. Phys. 14, 035009 (2012) [2] V. Kapaklis et al., Nature Nanotech 9, 514(2014) [3] E. Östman et al.,New J. Phys. 16, 053002 (2014) [4] E. Östman et al.,Thermal ordering in mesoscopic Ising chains, In manuscript.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129537083","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}

引用次数: 0

Exciton dissociation at organic small molecule donor-acceptor interfaces (Presentation Recording) 有机小分子供体-受体界面上的激子解离(演讲录音)

SPIE NanoScience + Engineering Pub Date : 2015-10-05 DOI: 10.1117/12.2188266

S. Robey

{"title":"Exciton dissociation at organic small molecule donor-acceptor interfaces (Presentation Recording)","authors":"S. Robey","doi":"10.1117/12.2188266","DOIUrl":"https://doi.org/10.1117/12.2188266","url":null,"abstract":"Exciton dissociation at organic semiconductor donor-acceptor (D-A) heterojunctions is critical for the performance of organic photovoltaic (OPV) structures. Interfacial charge separation and recombination processes control device efficiency. We have investigated these fundamental interfacial issues using time-resolved two-photon photoemission (TR-2PPE), coupled with the formation of well-controlled D-A structures by organic molecular beam epitaxy. The interfacial electronic and molecular structure of these model interfaces was well-characterized using scanning tunneling microscopy and ultraviolet photoemission. Exciton dissociation dynamics were investigated by using a sub-picosecond pump pulse to create Pc π→π* transitions, producing a population of singlet (S1) Pc excitons. The subsequent decay dynamics of this population was monitored via photoemission with a time-delayed UV pulse. For CuPcC60 interfaces, S1 exciton population decay in the interfacial CuPc layer was much faster than decay in the bulk due to interfacial charge separation. The rate constant for exciton dissociation was found to be ≈ 7 x 10 12 sec-1 (≈ 140 fs). Excitons that lose energy via intersystem crossing (ISC) to triplet levels dissociate approximately 500 to 1000 times slower. The dependence of exciton dissociation on separation was also studied. Exciton dissociation falls of rapidly with distance from the interface. Dissociation from the 2nd, and subsequent, layers of H2Pc is reduced by at least a factor of 10 from that in the interfacial layer. Finally, investigations of the relative efficiency for interfacial exciton dissociation by alternative acceptors based on perylene cores, (perylene tetracarboxylic dianhydride, or PTCDA) compared to fullerene-based acceptors such as C60 will also be discussed.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128309759","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}

引用次数: 0

Full-band structure modeling of the radiative and non-radiative properties of semiconductor materials and devices (Presentation Recording) 半导体材料和器件的辐射和非辐射特性的全频带结构建模(演示记录)

SPIE NanoScience + Engineering Pub Date : 2015-10-05 DOI: 10.1117/12.2190357

E. Bellotti, Hanqing Wen, B. Pinkie, M. Matsubara, F. Bertazzi

{"title":"Full-band structure modeling of the radiative and non-radiative properties of semiconductor materials and devices (Presentation Recording)","authors":"E. Bellotti, Hanqing Wen, B. Pinkie, M. Matsubara, F. Bertazzi","doi":"10.1117/12.2190357","DOIUrl":"https://doi.org/10.1117/12.2190357","url":null,"abstract":"Understanding the radiative and non-radiative properties of semiconductor materials is a prerequisite for optimizing the performance of existing light emitters and detectors and for developing new device architectures based on novel materials. Due to the ever increasing complexity of novel semiconductor systems and their relative technological immaturity, it is essential to have design tools and simulation strategies that include the details of the microscopic physics and their dependence on the macroscopic (continuum) variables in the macroscopic device models. Towards this end, we have developed a robust full-band structure based approach that can be used to study the intrinsic material radiative and non-radiative properties and evaluate the same characteristics of low-dimensional device structures. A parallel effort is being carried out to model the effect of substrate driven stress/strain and material quality (dislocations and defects) on microscopic quantities such as non-radiative recombination rate. Using this modeling approach, we have extensively studied the radiative and non-radiative properties of both elemental (Si and Ge) and compound semiconductors (HgCdTe, InGaAs, InAsSb and InGaN). In this work we outline the details of the modelling approach, specifically the challenges and advantages related to the use of the full-band description of the material electronic structure. We will present a detailed comparison of the radiative and Auger recombination rates as a function of temperature and doping for HgCdTe and InAsSb that are two important materials for infrared detectors and emitters. Furthermore we will discuss the role of non-radiatiave Auger recombination processes in explaining the performance of light emitter diodes. Finally we will present the extension of the model to low dimensional structures employed in a number of light emitter and detector structures.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126589956","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}

引用次数: 0

Understanding of increased diffuse scattering in regular arrays of fluctuating resonant particles (Presentation Recording) 理解波动共振粒子的规则阵列中增加的漫射散射(演讲记录)

SPIE NanoScience + Engineering Pub Date : 2015-10-05 DOI: 10.1117/12.2186283

A. Andryieuski, M. Petrov, A. Lavrinenko, S. Tretyakov

{"title":"Understanding of increased diffuse scattering in regular arrays of fluctuating resonant particles (Presentation Recording)","authors":"A. Andryieuski, M. Petrov, A. Lavrinenko, S. Tretyakov","doi":"10.1117/12.2186283","DOIUrl":"https://doi.org/10.1117/12.2186283","url":null,"abstract":"In this presentation we will discuss the analytical and numerical approaches to modeling electromagnetic properties of geometrically regular subwavelength 2D arrays of random resonant plasmonic particles. Amorphous metamaterials and metasurfaces attract interest of the scientific community due to promising technological implementations with cost-efficient methods of large-scale chemical nanoparticles synthesis as well as their self-organization. Random fluctuations of the particles size, shape, and/or composition are inevitable not only in the bottom-up synthesis, but also in conventional electron beam and photolithography fabrication. Despite the significant progress in large-scale fabrication, modeling and effective properties prediction of random/amorphous metamaterials and metasurfaces is still a challenge, which we address here. We present our results on analytical modelling of metasurfaces with regular periodic arrangements of resonant nanoparticles of random polarizability/size/material at normal plane-wave incidence. We show that randomness of the polarizability is related to increase in diffused scattering and we relate this phenomenon to a modification of the dipoles’ interaction constant. As a result, we obtain a simple analytical formula which describes diffuse scattering in such amorphous metasurfaces. Employing the supercell approach we numerically confirm the analytical results. The proposed approach can be easily extended from electrical dipole arrays and normal wave incidence to more general cases of electric and magnetic resonant particles and oblique incidence.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126036725","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}

引用次数: 0

Microscopic theory of the inverse Edelstein effect (Presentation Recording) 反Edelstein效应的微观理论(演讲记录)

SPIE NanoScience + Engineering Pub Date : 2015-10-05 DOI: 10.1117/12.2185847

R. Raimondi, K. Shen, G. Vignale

{"title":"Microscopic theory of the inverse Edelstein effect (Presentation Recording)","authors":"R. Raimondi, K. Shen, G. Vignale","doi":"10.1117/12.2185847","DOIUrl":"https://doi.org/10.1117/12.2185847","url":null,"abstract":"The spin Hall effect (SHE) and the inverse spin Hall effect (ISHE) are well established phenomena in current spintronics research. A third important effect is the current-induced spin polarization, which, within the Rashba model for a spin-orbit coupled two-dimensional disordered electron gas, has been predicted by Edelstein in 1990 and it is referred to as the Edelstein effect (EE). This effect is deeply connected to the above two effects thanks to a constraint dictated by the equation of motion. Less known is the inverse Edelstein effect (IEE), which is the Onsager reciprocal of the EE and according to which a charge current is generated by a non-equilibrium spin polarization. The IEE has been recently observed (Nature Commun. 4, 2944 (2013)) in a hybrid ferromagnetic-metal system. In this talk I provide a precise microscopic definition of the IEE and its description within the Rashba model. It turns out that the effect has a surprisingly simple interpretation when the spin-charge coupled drift-diffusion equations governing it are cast in the language of a SU(2) gauge theory, with the Rashba spin-orbit coupling playing the role of a generalized spin-dependent vector potential. After sketching briefly the derivation of the drift-diffusion equations, the latter are applied to the interpretation of the experiments. The role of spin-orbit coupling due to impurities is also considered, by showing that the strenght of the IEE can be controlled by the ratio of the spin relaxation rates associated to the two type of spin-orbit coupling.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134456809","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}

引用次数: 1

Colossal optical transmission through buried metal gratings (Presentation Recording) 通过埋地金属光栅的巨大光传输(演示记录)

SPIE NanoScience + Engineering Pub Date : 2015-10-05 DOI: 10.1117/12.2188504

C. Roberts, Runyu Liu, Xiang Zhao, Lan Yu, Xiuling Li, D. Wasserman, V. Podolskiy

{"title":"Colossal optical transmission through buried metal gratings (Presentation Recording)","authors":"C. Roberts, Runyu Liu, Xiang Zhao, Lan Yu, Xiuling Li, D. Wasserman, V. Podolskiy","doi":"10.1117/12.2188504","DOIUrl":"https://doi.org/10.1117/12.2188504","url":null,"abstract":"In Extraordinary Optical Transmission (EOT), a metallic film perforated with an array of [periodic] apertures exhibits transmission over 100% normalized to the total aperture area, at selected frequencies. EOT devices have potential applications as optical filters and as couplers in hybrid electro-optic contacts/devices. Traditional passive extraordinary optical transmission structures, typically demonstrate un-normalized transmission well below 50%, and are typically outperformed by simpler thin-film techniques. To overcome these limitations, we demonstrate a new breed of extraordinary optical transmission devices, by “burying” an extraordinary optical transmission grating in a dielectric matrix via a metal-assisted-chemical etching process. The resulting structure is an extraordinary optical transmission grating on top of a dielectric substrate with dielectric nano-pillars extruded through the grating apertures. These structures not only show significantly enhanced peak transmission when normalized to the open area of the metal film, but more importantly, peak transmission greater than that observed from the bare semiconductor surface. The structures were modeled using three-dimensional rigorous coupled wave analysis and characterized experimentally by Fourier transform infrared reflection and transmission spectroscopy, and the good agreement between the two has been demonstrated. The drastic enhancement of light transmission in our structures originates from structuring of high-index dielectric substrate, with pillars effectively guiding light through metal apertures.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132798919","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}

引用次数: 0

Metamaterial-based single pixel imaging system (Presentation Recording) 基于超材料的单像素成像系统(演示记录)

SPIE NanoScience + Engineering Pub Date : 2015-10-05 DOI: 10.1117/12.2189836

Willie J Padilla, C. Watts, Christian C. Nadell, J. Montoya, S. Krishna

{"title":"Metamaterial-based single pixel imaging system (Presentation Recording)","authors":"Willie J Padilla, C. Watts, Christian C. Nadell, J. Montoya, S. Krishna","doi":"10.1117/12.2189836","DOIUrl":"https://doi.org/10.1117/12.2189836","url":null,"abstract":"Single pixel cameras are useful imaging devices where it is difficult or infeasible to fashion focal plan arrays. For example in the Far Infrared (FIR) it is difficult to perform imaging by conventional detector arrays, owing to the cost and size of such an array. The typical single pixel camera uses a spatial light modulator (SLM) - placed in the conjugate image plane – and is used to sample various portions of the image. The spatially modulated light emerging from the SLM is then sent to a single detector where the light is condensed with suitable optics for detection. Conventional SLMs are either based on liquid crystals or digital mirror devices. As such these devices are limited in modulation speeds of order 30 kHz. Further there is little control over the type of light that is modulated. We present metamaterial based spatial light modulators which provide the ability to digitally encode images – with various measurement matrix coefficients – thus permitting high speed and fidelity imaging capability. In particular we use the Hadamard matrix and related S-matrix to encode images for single pixel imaging. Metamaterials thus permit imaging in regimes of the electromagnetic spectrum where conventional SLMs are not available. Additionally, metamaterials offer several salient features that are not available with commercial SLMs. For example, metamaterials may be used to enable hyperspectral, polarimetric, and phase sensitive imaging. We present the theory and experimental results of single pixel imaging with digital metamaterials in the far infrared and highlight the future of this exciting field.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132300927","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}

引用次数: 1

Thermoelectric pellets made of Si nanowires (Presentation Recording) 由硅纳米线制成的热电球(演示记录)

SPIE NanoScience + Engineering Pub Date : 2015-10-05 DOI: 10.1117/12.2192445

Kate J. Norris, G. Tompa, N. Sbrockey, N. Kobayashi

引用次数: 0

Evaluation of different processing steps on the dark current of electron-injection detectors (Presentation Recording) 不同处理步骤对电子注入探测器暗电流的影响(演讲记录)

SPIE NanoScience + Engineering Pub Date : 2015-10-05 DOI: 10.1117/12.2188755

M. Rezaei, S. Jang, H. Mohseni

引用次数: 0

Plasmonic laser sensors (Presentation Recording) 等离子体激光传感器(演示记录)

SPIE NanoScience + Engineering Pub Date : 2015-10-05 DOI: 10.1117/12.2186086

R. Ma, S. Ota, Yimin Li, Sui Yang, Xiang Zhang

{"title":"Plasmonic laser sensors (Presentation Recording)","authors":"R. Ma, S. Ota, Yimin Li, Sui Yang, Xiang Zhang","doi":"10.1117/12.2186086","DOIUrl":"https://doi.org/10.1117/12.2186086","url":null,"abstract":"Perhaps the most successful application of plasmonics to date has been in sensing, where the interaction of a nanoscale localized field with analytes leads to high-sensitivity detection in real time and in a label-free fashion. However, all previous designs have been based on passively excited surface plasmons, in which sensitivity is intrinsically limited by the low quality factors induced by metal losses. It has recently been proposed theoretically that surface plasmon sensors with active excitation (gain-enhanced) can achieve much higher sensitivities due to the amplification of the surface plasmons. Here, we experimentally demonstrate an active plasmon sensor that is free of metal losses and operating deep below the diffraction limit for visible light. Loss compensation leads to an intense and sharp lasing emission that is ultrasensitive to adsorbed molecules. We validated the efficacy of our sensor to detect explosives in air under normal conditions and have achieved a sub-part-per-billion detection limit, the lowest reported to date for plasmonic sensors with 2,4-dinitrotoluene and ammonium nitrate. The selectivity between 2,4-dinitrotoluene, ammoniumnitrate and nitrobenzene is on a par with other state-of-the-art explosives detectors. Our results show that monitoring the change of the lasing intensity is a superior method than monitoring the wavelength shift, as is widely used in passive surface plasmon sensors. We therefore envisage that nanoscopic sensors that make use of plasmonic lasing could become an important tool in security screening and biomolecular diagnostics.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122635312","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}

引用次数: 0