Local Probing of a Superconductor’s Quasiparticles and Bosonic Excitations with a Scanning Tunnelling Microscope

Complementary to scattering techniques, scanning tunnelling microscopy provides atomic-scale real space information about a material\u27s electronic state of matter. State-of-the-art designs of a scanning tunnelling microscope (STM) allow measurements at millikelvin temperatures with unprecedented energy resolution. Therefore, this instrument excels in probing the superconducting state at low temperatures and especially its local quasiparticle excitations as well as bosonic degrees of freedom

Quantitative methods for electron energy loss spectroscopy

[spa] Este trabajo explora las posibilidades analíticas que ofrece la técnica de espectroscopia electrónica de bajas pérdidas (low-loss EELS), capaces de revelar la configuración estructural de los más avanzados dispositivos semiconductores. El uso de modernos microscopios electrónicos de transmisión-barrido (STEM) nos permite obtener información espectroscópica a partir de volúmenes reducidos, hasta llegar a resolución atómica. Por ello, EELS es cada vez mas popular para la observación de los dispositivos semiconductores, a medida que los tamaños característicos de sus estructuras constituyentes se miniaturiza. Los espectros de pérdida de energía contienen mucha información: dado que el haz de electrones sufre unos bien conocidos procesos de dispersión inelástica, podemos trazar relaciones entre estos espectros y excitaciones elementales en la configuración atómica de los elementos y compuestos constituyentes de cada material. Se describe un marco teórico para el estudio del low-loss EELS: el modelo dieléctrico de dispersión inelástica, que toma en consideración las propiedades electrodinámicas del haz de electrones y la descripción mecano-cuántica de los materiales. Adicionalmente, se describen en detalle las herramientas utilizadas en el análisis de datos experimentales o la simulación teórica de espectros. Monitorizando las energías de band gap y plasmon en los datos experimentales de low-loss EELS se obtiene información directa sobre propiedades electrónicas de los materiales. Además, usando análisis Kramers-Kronig en los espectros se obtiene información dieléctrica que puede ser comparada con las simulaciones o con otras técnicas (ópticas). Se demuestra el uso de estas herramientas con una serie de estudios sobre estructuras basadas en nitruros del grupo-III. Por otro lado, el uso de algoritmos para el análisis multivariante permite separar las contribuciones individuales que se miden mezcladas en espectros de estructuras complicadas. Hemos utilizado estas avanzadas herramientas para el análisis de estructuras basadas en silicio que contienen nano-cristales embebidos en matrices dieléctricas.[eng] This thesis explores the analytical capabilities of low-loss electron energy loss spectroscopy (EELS), applied to disentangle the intimate configuration of advanced semiconductor heterostructures. Modern aberration corrected scanning transmission electron microscopy (STEM) allows extracting spectroscopic information from extremely constrained areas, down to atomic resolution. Because of this, EELS is becoming increasingly popular for the examination of novel semiconductor devices, as the characteristic size of their constituent structures shrinks. Energy-loss spectra contain a high amount of information, and since the electron beam undergoes well-known inelastic scattering processes, we can trace the features in these spectra down to elementary excitations in the atomic electronic configuration. In Chapter 1, the general theoretical framework for low-loss EELS is described. This formulation, the dielectric model of inelastic scattering, takes into account the electrodynamic properties of the fast electron beam and the quantum mechanical description of the materials. Low-loss EELS features are originated both from collective mode (plasmons) and single electron excitations (e.g. band gap), that contain relevant chemical and structural information. The nature of these excitations and the inelastic processes involved has to be taken into account in order to analyze experimental data or to perform simulations. The computational tools required to perform these tasks are presented in Chapter 2. Among them, calibration, deconvolution and Kramers-Kronig analysis (KKA) of the spectrum constitute the most relevant procedures, that ultimately help obtain the dielectric information in the form of a complex dielectric function (CDF). This information may be then compared to the one obtained by optical techniques or with the results from simulations. Additional techniques are explained, focusing first on multivariate analysis (MVA) algorithms that exploit the hyperspectral acquisition of EELS, i.e. spectrum imaging (SI) modes. Finally, an introduction to the density functional theory (DFT) simulations of the energy-loss spectrum is given. In Chapter 3, DFT simulations concerning (Al, Ga, In)N binary and ternary compounds are introduced. The prediction of properties observed in low-loss EELS of these semiconductor materials, such as the band gap energy, is improved in these calculations. Moreover, a super-cell approach allows to obtain the composition dependence of both band gap and plasmon energies from the theoretical dielectric response coefficients of ternary alloys. These results are exploited in the two following chapters, in which we experimentally probe structures based on group-III nitride binary and ternary compounds. In Chapter 4, two distributed Bragg reflector structures are examined (based upon AlN/GaN and InAlN/GaN multilayers, respectively) through different strategies for the characterization of composition from plasmon energy shift. Moreover; HAADF image simulation is used to corroborate he obtained results; plasmon width, band gap energy and other features are measured; and, KKA is performed to obtain the CDF of GaN. In Chapter 5, a multiple InGaN quantum well (QW) structure is examined. In these QWs (indium rich layers of a few nanometers in width), we carry out an analysis of the energy-loss spectrum taking into account delocalization and quantum confinement effects. We propose useful alternatives complementary to the study of plasmon energy, using KKA of the spectrum. Chapters 6 and 7 deal with the analysis of structures that present pure silicon-nanocrystals (Si-NCs) embedded in silicon-based dielectric matrices. Our aim is to study the properties of these nanoparticles individually, but the measured low-loss spectrum always contains mixed signatures from the embedding matrix as well. In this scenario, Chapter 6 proposes the most straightforward solution; using a model-based fit that contains two peaks. Using this strategy, the Si-NCs embedded in an Er-doped SiO2 layer are characterized. Another strategy, presented in Chapter 7, uses computer-vision tools and MVA algorithms in low-loss EELS-SIs to separate the signature spectra of the Si-NCs. The advantages and drawbacks of this technique are revealed through its application to three different matrices (SiO2, Si3N4 and SiC). Moreover, the application of KKA to the MVA results is demonstrated, which allows to extract CDFs for the Si-NCs and surrounding matrices

Development of stable and efficient visible-light-driven photocatalysts through heteroatom doping strategy

The photocatalysis is one of the most promising sustainable technologies to tackle the challenges of environmental pollutions. However, traditional photocatalysts such as TiO2 exhibit the narrow light absorption range and low quantum efficiency. These drawbacks seriously limit their practical applications. The development of high-efficiency photocatalysts with large specific surface area and high photocatalytic activity has become the key to the photocatalysis technology. Doping heteroatoms into the crystal of photocatalyst is an effective way to improve its photocatalytic activity. With appropriate photocatalyst design, the dopants in moderate doping concentration can optimise the catalysts in the following multiple aspects: (i) with extra dopant energy level in the bandgap of semiconductor, dopants can reduce the bandgap to broaden the light absorption of the photocatalysts; (ii) dopants can intentionally shift the valence band position to improve the photooxidation capability of the catalysts; (iii) dopants can suppress the photo-excited electrons and holes recombination, which results in an enhanced quantum efficiency; (iv) in plasmonic photocatalysts, dopants can modify the electronic structure of the plasmonic crystal to enhance the photo-excited charge carrier generation and increase the energy of the excited charge carriers. In this thesis, the heteroatom doping strategy has been used to enhance the dye photodegradation performance of photocatalysts. With the help of molecular and electronic structure analyses, the mechanisms underpinning the enhancement of photocatalytic performance are elucidated. In chapter 3, the Zn doped C3N4 has been successfully synthesized in eutectic ZnCl2-KCl salts mixture for the first time. The low melting temperature of ZnCl2- KCl promotes the dispersion of the organic precursors, therefore creating a specific surface area at least ~7.4 times larger than the bulk C3N4 synthesized via the conventional thermal polymerization method in air (C3N4-M-Air). The significant improvement in the photocatalytic activity is achieved through locating the melting point of the salt mixture within the temperature window between dicyandiamide and melamine oligomer formation steps in the polycondensation process. Using dicyandiamide as the precursor shifts the valence band maximum (VBM) of the prepared C3N4 (C3N4-D) positively, therefore enhancing the oxidation capability of the photocatalysts. The Zn dopants at the interstitial site of C3N4 in an appropriate concentration suppress the photo-excited electron-hole recombination, which significantly contributes to the high photocatalytic activity. The optimal sample C3N4-D shows ~4.2 times larger photocurrent density and ~1.46 times longer carrier lifetime than the C3N4-M-Air. In photocatalytic methyl orange (MO) degradation, the pseudo-first reaction rate constant of C3N4-D is ~4.15 times higher than that of the C3N4-M-Air control group. In chapter 4, the combined effects of Cl doping and agitation are used for the first time to improve the photocatalytic performance of C3N4 synthesized via solvothermal method. The enhanced photocatalytic RhB degradation activity is attributed to the optimized electronic structure, enlarged specific surface area and balanced interstitial/substitutional Cl doping. More importantly, it is found that the preferred doping site for Cl dopants is strongly controlled by the agitation rate. The atomic ratio of interstitial over substitutional Cl dopants shows a U shape correlation with the agitation rate. Furthermore, the different effects of interstitial and substitutional Cl dopants on the photocatalytic activity are distinguished and elucidated. The optimal synthesis condition for Cl-doped C3N4 is associated with a moderate agitation rate of 60 rpm (60-C3N4). Under 60 rpm agitation during the synthesis, the 60-C3N4 exhibits remarkably larger specific surface area, stronger photo-oxidation capability, reduced bandgap and suppressed electron-hole recombination comparing with the control group g-C3N4 synthesized via conventional thermal polycondensation method. An outstanding photocatalytic RhB degradation performance is therefore observed for 60-C3N4 with ~37-fold higher pseudo-first reaction rate constant than the control group conventional g-C3N4 sample. In chapter 5, the C doped TiN/ultrathin carbon layer has been synthesized via the calcination of TiCl4/urea mixture and shows the prominent plasmonic photocatalytic RhB degradation performance under visible light irradiation. Based on the systematic investigations on the preparation conditions, it is found that the urea amount and calcination temperature are the two critical factors determining the chemical composition and crystal size of TiN nanoparticles. In the optimal condition with 3.0g urea and 1100 o C synthesis temperature, the TiN nanocrystals with the mean size of ~37 nm are formed and well-dispersed on N doped ultrathin carbon layer layers. The larger amount of urea and higher synthesis temperature result in the increase of TiN nanoparticle size. Moreover, it is proven that the appropriate amount of C doping can enhance the plasmonic photocatalytic activity of TiN. Based on DFT calculation, the C sp band introduced into TiN band structure can enhance the interband excitation of electrons, which results in the excited holes with higher quantity and energy. In visible light driven RhB photodegradation, the optimal C doped TiN/ultrathin carbon layer sample shows the higher first-order reaction rate constant than the benchmark rutile TiO2 and C3N4/TiO2 by ~34.2 and 6.5 times, respectively

Modes propres plasmon de surface révélés par spectroscopies d'électrons rapides (de systèmes modèles simples vers des systèmes complexes)

Les plasmons de surface (SP) sont des excitations mêlant électrons et photons localisées aux surfaceset interfaces métalliques. On peut les voir classiquement comme les modes électromagnétiquespropres d un ensemble constitué d un métal et d un diélectrique. Cette thèse se base sur la capacitéofferte par les techniques de spectroscopie utilisant des électrons rapides disponibles dans un microscopeélectronique à balayage en transmission (STEM), de cartographier, dans une large gammespectrale et avec une résolution spatiale nanométrique, les modes propres SP. Une telle capacitéa été démontrée séparément, durant ces dernières années, par des expériences de spectroscopie depertes d énergie d électrons (EELS), qui mesurent l énergie perdue par des électrons rapides intéragissantavec un échantillon, et de cathodoluminescence (CL), qui mesurent l énergie réémisepar l échantillon par l intermédiaire de photons, toutes deux résolues spatialement. Dans le cas del EELS, ces résultats expérimentaux sont aujourd hui interprétables à l aide d analyses théoriquesconvaincantes tendant à prouver que la quantité mesurée dans une telle expérience peut être interprétéede façon sûre en terme de modes propres de surface de l échantillon. Afin d élargir une telleinterprétation aux techniques de spectroscopies utilisant des électrons rapides en général, j ai effectuédes expériences combinées d EELS et de CL résolues spatialement sur une nanoparticle uniquesimple (un nanoprisme d or). J ai montré que les résultats offerts par ces deux techniques présententde fortes similitudes mais également de légères différences, ce qui est confirmé par des simulationsnumériques. J ai étendu l analyse théorique du signal EELS au signal CL, et ai montré que la CLcartographie, tout comme l EELS, les modes de surface radiatifs du sytème, mais avec des propriétésspectrales légèrement différentes. Ce travail constitue une preuve de principe clarifiant les quantitésmesurées en EELS et CL sur des systèmes métal-dielectriques. Ces dernières sont démontrées êtrerespectivement des équivalents nanométriques des spectroscopies d extinction et de diffusion de lalumière. Basé sur cette interprétation, j ai utilisé l EELS pour dévoiler les modes propres SP demilieux métalliques aléatoires (dans notre cas, des films semicontinus métalliques avant le seuil depercolation). Ces modes propres constituent une problématique de longue date dans le domainede la nanooptique. J ai directement identifié ces modes par des mesures et le traitement de leursrésultats. J ai complètement caractérisé ces modes propres via les variations spatiales de l intensitéliée à leur champ électrique, une énergie propre et un taux de relaxation. Ce faisant, j ai montré quela géométrie fractale du milieu, dont la prédominance croit au fur et à mesure que l on s approchede la percolation, est responsable de l existence de modes propres de type aléatoire à basse énergie.Surface Plasmons (SP) are elementary excitations mixing electrons and photons at metal surfaces,which can be seen in a classical electrodynamics framework as electromagnetic surface eigenmodesof a metal-dielectric system. The present work bases on the ability of mapping SP eigenmodes withnanometric spatial resolution over a broad spectral range using spatially resolved fast electron basedspectroscopies in a Scanning Transmission Electron Microscope (STEM). Such an ability has beenseparately demonstrated during the last few years by many spatially resolved experiments of ElectronEnergy Loss Spectroscopy (EELS), which measures the energy lost by fast electrons interactingwith the sample, and CathodoLuminescence (CL), which measures the energy released by subsequentlyemitted photons. In the case of EELS, the experimental results are today well accountedfor by strong theory elements which tend to show that the quantity measured in an experiment canbe safely interpreted in terms of the surface eigenmodes of the sample. In order to broaden thisinterpretation to fast electron based spectroscopies in general, I have performed combined spatiallyresolved EELS and CL experiments on a simple single nanoparticle (a gold nanoprism). I have shownthat EELS and CL results bear strong similarities but also slight differences, which is confirmed bynumerical simulations. I have extended the theoretical analysis of EELS to CL to show that CLmaps equally well than EELS the radiative surface eigenmodes, yet with slightly different spectralfeatures. This work is a proof of principle clarifiying the quantities measured in EELS and CL,which are shown to be respectively some nanometric equivalent of extinction and scattering spectroscopieswhen applied to metal-dielectric systems. Based on this interpretation, I have applied EELSto reveal the SP eigenmodes of random metallic media (in our case, semicontinuous metal films beforethe percolation threshold). These SP eigenmodes constitute a long standing issue in nanooptics.I have directly identified the eigenmodes from measurements and data processing. I havefully characterized these eigenmodes experimentally through an electric field intensity pattern, aneigenenergy and a relaxation rate. Doing so, I have shown that the fractal geometry of the medium,which grows towards the percolation, induces random-like eigenmodes in the system at low energies.Keywords: Surface plasmons, fast electron based spectroscopies, scanning transmission electronmicroscopy, disordered mediaPARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

Nanofabrication

We face many challenges in the 21st century, such as sustainably meeting the world's growing demand for energy and consumer goods. I believe that new developments in science and technology will help solve many of these problems. Nanofabrication is one of the keys to the development of novel materials, devices and systems. Precise control of nanomaterials, nanostructures, nanodevices and their performances is essential for future innovations in technology. The book "Nanofabrication" provides the latest research developments in nanofabrication of organic and inorganic materials, biomaterials and hybrid materials. I hope that "Nanofabrication" will contribute to creating a brighter future for the next generation

Eigenmode Analysis in Plasmonics: Application to Second Harmonic Generation and Electron Energy Loss Spectroscopy

Eigenmodes are central to the study of resonant phenomena in all areas of physics. However, their use in nano-optics seems to have been hindered and delayed for various reasons. First, due to their small size, the response of nanostructures to a far-field optical excitation is mainly dipolar. Thus, preliminary studies of nanosystems through optical methods meant that only very few eigenmodes of the system were probed, and a complete eigenmode theory was not required. Second, rigorously defining eigenmodes of an open and lossy cavity is far from trivial. Finally, only few geometries allow for an analytical solution of Maxwellâs equations that can be expressed in terms of modes, rendering the use of numerical methods mandatory to study non-trivial shapes. On the other hand, modern spectroscopy techniques based on fast electron excitation, instead of optical excitation, allow going beyond the above-mentioned dipolar regime and enable the observation of high order modes. In addition, the generation of second harmonic light (SHG) by nanoparticles permits revealing higher order modes that weakly couple to planewave far-field probing. Thus, to be able to analyze the data collected with such experimental methods and comprehend them in order to make appropriate nanostructure designs, one needs to develop suitable numerical tools for the computation of eigenmodes. This is the focus of this thesis, where eigenmodes are used throughout to analyze and understand experimental and numerical results. First, different approaches used to define and compute eigenmodes are presented in details together with the surface integral equation method used in this manuscript. The second chapter presents the use of eigenmodes to study the SHG in plasmonic nanostructures. A single mode is used as an SHG source to disentangle the modal contributions from different SHG channels. For three different nanostructures, the dipolar mode gives a pure quadrupolar second harmonic (SH) response. Then, the interplay of dipolar and quadrupolar SH radiations in nanorods of different sizes is revealed through a multipolar analysis, explaining the experimental observation of the flip between forward and backward maximum SH emissions. Finally, the dynamics of the SHG from a silver nanorod generated by short pulses is investigated. By tuning the spectral position and width of the pulses, the dynamics of a single mode is observed, both in the linear and SH responses, and fits extremely well with a harmonic oscillator model. The last chapter presents the utilization of the eigenmodes to interpret electron energy loss spectroscopy (EELS) measurements. An alternative approach to compute EELS signal is presented, revealing the different paths through which the energy of the electron is dissipated. Instead of computing the work done by the electron against the scattered electric field, the Ohmic and the radiation losses are evaluated. Then, heterodimers with several shapes and compositions are studied. A rich variety of modes is found, due to the additional degree of freedom associated with the different metals. Dolmen shaped nanostructures are also investigated in great details. A rigorous analysis of the eigenmode evolution when the central horizontal nanorod is moved is performed. Finally, we study the EELS for three iterations of a Koch snowflake nanoantenna. The evolution of the modes with the iteration of the fractal is analysed and the modes are linked to the experimental EELS ma

Nanoestruturas baseadas em ZnO e GaN para aplicações optoeletrónicas : síntese e caracterização

Wide bandgap semiconductors, such as GaN and ZnO, are materials with a wide range of applications in several important technological areas including lighting, transparent electronics, sensors, catalysis or photovoltaics. This thesis focuses on the study of GaN and ZnO, including related compounds. In the first case, the emphasis is given to the incorporation of rare-earth (RE) ions (4fn) into the nitride hosts envisaging to contribute for the development of “all-nitride” solid state lighting devices. GaN and related III-nitrides ternary alloys appear as excellent hosts for the incorporation of these ions. The use of RE ions is motivated by the electromagnetic widespread spectral range (from the ultraviolet to the near infrared) covered by the intraionic radiative relaxation of the trivalent charged ions. Ion implantation appears as an alternative approach to doping since it allows the introduction of impurities in a controlled way and without solubility limits. GaN samples with different dimensionalities were analysed and their influence in the luminescence properties of the RE3+ was investigated. Photoluminescence (PL) measurements revealed that after thermal annealing a successful optical activation of the RE3+ was achieved for the samples implanted with the different RE3+. A detailed spectroscopic analysis of RE3+ luminescent tarnsitions is presented by using temperature dependent steady-state PL, room temperature PL excitation and time resolved PL. This thesis also aims to the growth and characterization of ZnO micro and nanostructures, through a new growth technique designated by laser assisted flow deposition (LAFD). LAFD is a very high yield method based on a vapour-solid mechanism that enables the growth of ZnO crystals in a very short timescale. LAFD was used in the growth of wurtzite micro/nanocrystalline ZnO with different morphologies (nanoparticles, tetrapods and microrods) as revealed by the extensive morphological characterization. Moreover, structural analysis evidenced the high crystalline quality of the produced crystals. The optical properties of the as-grown ZnO crystals were fully investigated by luminescence techniques, which revealed a high optical quality of the LAFD produced ZnO. In addition to the unintentionally doped micro/nanocrystals, ZnO/Ag and ZnO/carbon nanotubes (CNT) composite structures were also synthesized by LAFD. Silver-related spherical particles were found to be inhomogeneously distributed at the microrods surface, accumulating at the rods tips and promoting the ZnO nanorods re-nucleation. For the case of the ZnO/CNT composites two main approaches were adopted: i) a direct deposition of ZnO particles on the surface of vertically aligned multi-walled carbon nanotubes (VACNTs) forests without employing any additional catalyst and ii) ZnO/CNT buckypaper nanocomposites. It was found that the use of the LAFD technique carried out in framework of the first approach preserves the CNTs structure, their alignment, and avoids the collapse of the VACNTs array, which is a major advantage of this method. Additionally, taking into account that a crucial step in designing modern optoelectronic devices is to accomplish bandgap engineering, the optical properties of CdxZn1-xO alloy were also evaluated. A tuning of the ZnO bandgap towards the visible spectral region was accomplished by alloying this semiconductor with CdO. Finally, the potential application of the LAFD produced ZnO structures in the photocatalysis and photovoltaic fields was tested.Os semicondutores de elevado hiato energético, como é o caso do GaN e do ZnO, são materiais com aplicações em diversas áreas tecnológicas, que incluem, por exemplo, iluminação, eletrónica transparente, sensores, catalisadores ou fotovoltaicos. Esta tese é dedicada ao estudo de materiais baseados em GaN e ZnO, sendo dada ênfase à incorporação de iões terras-raras (RE) nas matrizes de nitretos, com a finalidade de contribuir para o desenvolvimento de dispositivos de iluminação de estado sólido. O uso dos iões RE é motivado pelas suas emissões intraiónicas abrangendo uma ampla gama espectral (do ultravioleta ao infravermelho próximo), quando estão no seu estado de carga trivalente. A implantação iónica surge como uma alternativa para a dopagem destes materiais, uma vez que permite a introdução de dopantes de uma forma controlada e independente dos limites de solubilidade dos iões nas matrizes. Amostras de GaN com diferentes dimensionalidades foram analisadas e a sua influência nas propriedades luminescentes dos RE3+ foi investigada. Medidas de fotoluminescência (PL) revelaram que, depois de um tratamento térmico, a ativação ótica dos iões foi bem-sucedida para as amostras implantadas com os diferentes iões. Uma análise espectroscópica detalhada das transições luminescentes dos RE3+ foi realizada usando técnicas como a PL em estado estacionário e transiente e excitação da fotoluminescência. Outro objetivo desta tese foi o crescimento e caracterização de micro e nanoestruturas de ZnO, recorrendo a uma nova técnica de crescimento designada por deposição de fluxo assistida por laser (LAFD). Este é um método com elevado rendimento, baseado num mecanismo sólido-vapor, que permite o crescimento de ZnO com diferentes morfologias (nanopartíclulas, tetrapodes e microfios). A sua análise estrutural pôs em evidência a excelente qualidade cristalina do ZnO produzido por esta técnica. As propriedades óticas foram também investigadas através de fotoluminescência, revelando a sua elevada qualidade ótica. Para além dos cristais não dopados intencionalmente, foram ainda preparados compósitos com prata e nanotubos de carbono (CNTs). No primeiro caso, foram observadas partículas esféricas de prata distribuídas de uma forma não uniforme na superfície dos microfios, mostrando uma tendência para se acumularem no topo destes e promovendo a sua renucleação. No caso dos compósitos ZnO/CNTs, foram usadas duas abordagens: i) deposição de partículas de ZnO diretamente no topo dos CNTs alinhados verticalmente, sem a utilização de nenhum catalisador adicional, e ii) produção de ZnO/CNTs buckypapers. No primeiro caso, a técnica de LAFD provou manter o alinhamento dos CNTs, evitando o seu colapso, sendo esta uma vantagem do método usado. Adicionalmente, tendo em consideração a importância do controlo do hiato energético dos materiais a ser aplicados em dispositivos optoelectrónicos, foram também estudadas as propriedades óticas da liga CdxZn1-xO. Devido ao aumento da fração molar de CdO na liga ternária observou-se um desvio do hiato do ZnO para a região visível do espetro eletromagnético. Finalmente, as estruturas de ZnO crescidas por LAFD foram testadas em dispositivos fotovoltaicos e em estudos de fotocatálisePrograma Doutoral em Nanociências e Nanotecnologi

37th Rocky Mountain Conference on Analytical Chemistry

Final program, abstracts, and information about the 37th annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, July 23-27, 1995