Made available in DSpace on 2014-12-17T14:54:58Z (GMT). No. of bitstreams: 1 DaviBB_DISSERT_1-70.pdf: 4567680 bytes, checksum: 150ff5afc1806ca374278b4c00a1f5a3 (MD5) Previous issue date: 2010-12-06 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Metamaterials exhibiting negative refraction have attracted a great amount of attention in recent years mostly due to their exquisite electromagnetic properties. These materials are artificial structures that exhibit characteristics not found in nature. It is possible to obtain a metamaterial by combining artificial structures periodically. We investigated the unique properties of Split Ring Resonators, High impedance Surfaces and Frequency Selective Surfaces and composite metamaterials. We have successfully demonstrated the practical use of these structures in antennas and circuits. We experimentally confirmed that composite metamaterial can improve the performance of the structures considered in this thesis, at the frequencies where electromagnetic band gap transmission takes place

Made available in DSpace on 2014-12-17T14:55:12Z (GMT). No. of bitstreams: 1 HumbertoDA_TESE.pdf: 4762435 bytes, checksum: 20aae983d6895db90a85b0e2b107200f (MD5) Previous issue date: 2013-09-02 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In the globalized world modern telecommunications have assumed key role within the company, causing a large increase in demand for the wireless technology of communication, which has been happening in recent years have greatly increased the number of applications using this technology. Due to this demand, new materials are developed to enable new control mechanisms and propagation of electromagnetic waves. The research to develop new technologies for wireless communication presents a multidisciplinary study that covers from the new geometries for passive antennas, active up to the development of materials for devices that improve the performance at the frequency range of operation. Recently, planar antennas have attracted interest due to their characteristics and advantages when compared with other types of antennas. In the area of mobile communications the need for antennas of this type has become increasingly used, due to intensive development, which needs to operate in multifrequency antennas and broadband. The microstrip antennas have narrow bandwidth due to the dielectric losses generated by irradiation. Another limitation is the degradation of the radiation pattern due to the generation of surface waves in the substrate. Some techniques have been developed to minimize this limitation of bandwidth, such as the study of type materials PBG - Photonic Band Gap, to form the dielectric material. This work has as main objective the development project of a slot resonator with multiple layers and use the type PBG substrate, which carried out the optimization from the numerical analysis and then designed the device initially proposed for the band electromagnetic spectrum between 3-9 GHz, which basically includes the band S to X. Was used as the dielectric material RT/Duroid 5870 and RT/Duroid 6010.LM where both are laminated ceramic-filled PTFE dielectric constants 2.33 and 10.2, respectively. Through an experimental investigation was conducted an analysis of the simulated versus measured by observing the behavior of the radiation characteristics from the height variation of the dielectric multilayer substrates. We also used the LTT method resonators structures rectangular slot with multiple layers of material photonic PBG in order to obtain the resonance frequency and the entire theory involving the electromagnetic parameters of the structure under consideration. xviii The analysis developed in this work was performed using the method LTT - Transverse Transmission Line, in the field of Fourier transform that uses a component propagating in the y direction (transverse to the real direction of propagation z), thus treating the general equations of the fields electric and magnetic and function. The PBG theory is applied to obtain the relative permittivity of the polarizations for the sep photonic composite substrates material. The results are obtained with the commercial software Ansoft HFSS, used for accurate analysis of the electromagnetic behavior of the planar device under study through the Finite Element Method (FEM). Numerical computational results are presented in graphical form in two and three dimensions, playing in the parameters of return loss, frequency of radiation and radiation diagram, radiation efficiency and surface current for the device under study, and have as substrates, photonic materials and had been simulated in an appropriate computational tool. With respect to the planar device design study are presented in the simulated and measured results that show good agreement with measurements made. These results are mainly in the identification of resonance modes and determining the characteristics of the designed device, such as resonant frequency, return loss and radiation pattern / No mundo globalizado moderno, as telecomunica??es assumiram um papel fundamental dentro das sociedades, provocando um grande aumento da demanda por tecnologia de comunica??o sem fio, isto vem acontecendo nos ?ltimos anos e tem aumentado bastante o n?mero de aplica??es que utilizam esta tecnologia. Em decorr?ncia dessa demanda, novos materiais s?o desenvolvidos no sentido de possibilitar novos mecanismos de controle e propaga??o de ondas eletromagn?ticas. A pesquisa para o desenvolvimento de novas tecnologias para comunica??o sem fios apresenta um car?ter multidisciplinar que abrange desde o estudo de novas geometrias para antenas passivas e ativas at? o de desenvolvimento de materiais para dispositivos que melhorem o desempenho naquela faixa de frequ?ncia de opera??o. Recentemente as antenas planares tem despertado interesses devido as suas caracter?sticas e vantagens que oferecem quando comparadas com os demais tipos de antenas. Na ?rea de comunica??es m?veis a necessidade de antenas desse tipo tem se tornado cada vez maior, devido ao seu intenso desenvolvimento, que necessita de antenas que operem em multifrequ?ncia e em banda larga. As antenas de microfita apresentam largura de banda estreita devido ?s perdas no diel?trico geradas pela irradia??o. Outra limita??o ? a degrada??o do diagrama de irradia??o devido ? gera??o de ondas de superf?cie no substrato. Algumas t?cnicas est?o sendo desenvolvidas para minimizar esta limita??o de banda, como ? o caso do estudo de materiais do tipo PBG Photonic Band Gap, para compor o material diel?trico. Este trabalho tem como objetivo principal o desenvolvimento do projeto de um ressoador de fenda com m?ltiplas camadas e com a utiliza??o de substrato do tipo PBG, onde foi realizada a otimiza??o a partir da analise num?rica e em seguida, projetado o dispositivo proposto inicialmente para a faixa do espectro eletromagn?tico compreendida entre 3-9 GHz, que inclui basicamente a banda S at? X. Foi utilizado como material diel?trico o RT/Duroid 5870 e RT/Duroid 6010.2LM onde ambos s?o laminados cer?micos PTFE com constantes diel?tricas de 2.33 e 10.2, respectivamente. Atrav?s de uma investiga??o experimental foi realizada uma an?lise dos resultados simulados versus medidos observando o comportamento das xvi caracter?sticas de radia??o a partir da varia??o da altura das multicamadas de subtrato diel?trico. Foi utilizado tamb?m o m?todo LTT ?s estruturas ressoadoras retangulares de fenda com m?ltiplas camadas, para a obten??o da freq??ncia de resson?ncia bem como toda a teoria que envolva os par?metros eletromagn?ticos da estrutura em estudo. As an?lises desenvolvidas neste trabalho foram realizadas com utiliza??o do m?todo LTT Linha de Transmiss?o Transversa, no dom?nio da Transformada de Fourier que utiliza uma componente de propaga??o na dire??o y (transversa ? dire??o real de propaga??o z), tratando assim as equa??es gerais dos campos el?tricos e magn?ticos em fun??o de yE e yH . A teoria PBG ser? aplicada para a obten??o da permissividade relativa para as polariza??es s e p dos substratos compostos de material fot?nico. Os resultados s?o obtidos com o software comercial Ansoft HFSS, usado para a an?lise precisa do comportamento eletromagn?tico do dispositivo planar em estudo, por meio do M?todo dos Elementos Finitos (FEM). Resultados num?rico-computacionais s?o apresentados em forma de gr?fico em duas e tr?s dimens?es, para aos par?metros de perda de retorno, frequ?ncia de radia??o, e diagrama de radia??o, efici?ncia de radia??o e densidade superficial de corrente para o dispositivo em estudo, e que tem como substratos, materiais fot?nicos e que fora simulado em uma ferramenta computacional apropriada. . No que diz respeito ao projeto do dispositivo planar em estudo s?o apresentados os resultados medidos e os simulados que apresentam boa concord?ncia com as medi??es efetuadas. Estes resultados consistem principalmente na identifica??o dos modos de resson?ncia e na determina??o das caracter?sticas do dispositivo projetado, como freq??ncia de resson?ncia, perda de retorno e diagrama de radia??o

Technology scaling beyond Moore’s law demands cutting-edge solutions of the gate length scaling in sub-10 nm regime for low power high speed operations. Recently SOI technology has received considerable attention, however manufacturable solutions in sub-10 nm technologies are not yet known for future nanoelectronics. Therefore, to continue scalinginsub-10 nm region, new one(1D) and two dimensional(2D) “nano-materials” and engineering are expected to keep its pace. However, significant challenges must be overcome for nano-material properties in carrier transport to be useful in future silicon nanotechnology. Thus, it is very important to understand and modulate their electronic band structure and transport properties for low power nanoelectronics applications. This thesis tries to provide solutions for some problems in this area. In recent times, one dimensional Silicon nanowire has emerged as a building block for the next generation nano-electronic devices as it can accommodate multiple gate transistor architecture with excellent electrostatic integrity. However as the experimental study of various energy band parameters at the nanoscale regime is extremely challenging, usually one relies on the atomic level simulations, the results of which are at par with the experimental observations. Two such parameters are the band gap and effective mass, which are of pioneer importance for the understanding of the current transport mechanism. Although there exists a large number of empirical relations of the band gap in relaxed Silicon nanowire, however there is a growing demand for the development of a physics based analytical model to standardize different energy band parameters which particularly demands its application in TCAD software for predicting different electrical characteristics of novel devices and its strained counterpart to increase the device characteristics significantly without changing the device architecture. In the first part of this work reports the analytical modeling of energy band gap and electron transport effective mass of relaxed and strained Silicon nanowires in various crystallographic directions for future nanoelectronics. The technology scaling of gate length in beyond Moore’s law devices also demands the SOI body thickness, TSi0 which is essentially very challenging task in nano-device engineering. To overcome this circumstance, two dimensional crystals in atomically thin layered materials have found great attention for future nanolectronics device applications. Graphene, one layer of Graphite, is such 2D materials which have found potentiality in high speed nanoelectronics applications due to its several unique electronic properties. However, the zero band gap in pure Graphene makes it limited in switching device or transistor applications. Thus, opening and tailoring a band gap has become a highly pursued topic in recent graphene research. The second part of this work reports atomistic simulation based real and complex band structure properties Graphene-Boron nitride heterobilayer and Boron Nitride embedded Graphene nanoribbons which can improve the grapheme and its nanoribbon band structure properties without changing their originality. This part also reports the direct band-to-band tunneling phenomena through the complex band structures and their applications in tunnel field effect transistors(TFETs) which has emerged as a strong candidate for next generation low-stand by power(LSTP) applications due to its sub-60mV/dec Sub threshold slope(SS). As the direct band-to-band tunneling(BTBT) is improbable in Silicon(either its bulk or nanowire form), it is difficult to achieve superior TFET characteristics(i.e., very low SS and high ON cur-rent) from the Silicon TFETs. Whereas, it is explored that much high ON current and very low subthreshold slope in hybrid Graphene based TFET characteristics open a new prospect in future TFETs. The investigations on ultrathin body materials also call for a need to explore new 2D materials with finite band gap and their various nanostructures for future nanoelectronic applications in order to replace conventional Silicon. In the third part of this report, we have investigated the electronic and dielectric properties of semiconducting layered Transition metal dichalcogenide materials (MX2)(M=Mo, W;X =S, Se, Te) which has recently emerged as a promising alternative to Si as channel materials for CMOS devices. Five layered MX2 materials(exceptWTe2)in their 2D sheet and 1D nanoribbon forms are considered to study the real and imaginary band structure of thoseMX2 materials by atomistic simulations. Studying the complex dispersion properties, it is shown that all the five MX2 support direct BTBT in their monolayer sheet forms and offer an average ON current and subthresholdslopeof150 A/mand4 mV/dec, respectively. However, onlytheMoTe2 support direct BTBT in its nanoribbon form, whereas the direct BTBT possibility in MoS2 and MoSe2 depends on the number of layers or applied uniaxial strain. WX2 nanoribbons are shown to be non-suitable for efficient TFET operation. Reasonably high tunneling current in these MX2 shows that these can take advantage over conventional Silicon in future tunnel field effect transistor applications.

Technology scaling beyond Moore’s law demands cutting-edge solutions of the gate length scaling in sub-10 nm regime for low power high speed operations. Recently SOI technology has received considerable attention, however manufacturable solutions in sub-10 nm technologies are not yet known for future nanoelectronics. Therefore, to continue scalinginsub-10 nm region, new one(1D) and two dimensional(2D) “nano-materials” and engineering are expected to keep its pace. However, significant challenges must be overcome for nano-material properties in carrier transport to be useful in future silicon nanotechnology. Thus, it is very important to understand and modulate their electronic band structure and transport properties for low power nanoelectronics applications. This thesis tries to provide solutions for some problems in this area. In recent times, one dimensional Silicon nanowire has emerged as a building block for the next generation nano-electronic devices as it can accommodate multiple gate transistor architecture with excellent electrostatic integrity. However as the experimental study of various energy band parameters at the nanoscale regime is extremely challenging, usually one relies on the atomic level simulations, the results of which are at par with the experimental observations. Two such parameters are the band gap and effective mass, which are of pioneer importance for the understanding of the current transport mechanism. Although there exists a large number of empirical relations of the band gap in relaxed Silicon nanowire, however there is a growing demand for the development of a physics based analytical model to standardize different energy band parameters which particularly demands its application in TCAD software for predicting different electrical characteristics of novel devices and its strained counterpart to increase the device characteristics significantly without changing the device architecture. In the first part of this work reports the analytical modeling of energy band gap and electron transport effective mass of relaxed and strained Silicon nanowires in various crystallographic directions for future nanoelectronics. The technology scaling of gate length in beyond Moore’s law devices also demands the SOI body thickness, TSi0 which is essentially very challenging task in nano-device engineering. To overcome this circumstance, two dimensional crystals in atomically thin layered materials have found great attention for future nanolectronics device applications. Graphene, one layer of Graphite, is such 2D materials which have found potentiality in high speed nanoelectronics applications due to its several unique electronic properties. However, the zero band gap in pure Graphene makes it limited in switching device or transistor applications. Thus, opening and tailoring a band gap has become a highly pursued topic in recent graphene research. The second part of this work reports atomistic simulation based real and complex band structure properties Graphene-Boron nitride heterobilayer and Boron Nitride embedded Graphene nanoribbons which can improve the grapheme and its nanoribbon band structure properties without changing their originality. This part also reports the direct band-to-band tunneling phenomena through the complex band structures and their applications in tunnel field effect transistors(TFETs) which has emerged as a strong candidate for next generation low-stand by power(LSTP) applications due to its sub-60mV/dec Sub threshold slope(SS). As the direct band-to-band tunneling(BTBT) is improbable in Silicon(either its bulk or nanowire form), it is difficult to achieve superior TFET characteristics(i.e., very low SS and high ON cur-rent) from the Silicon TFETs. Whereas, it is explored that much high ON current and very low subthreshold slope in hybrid Graphene based TFET characteristics open a new prospect in future TFETs. The investigations on ultrathin body materials also call for a need to explore new 2D materials with finite band gap and their various nanostructures for future nanoelectronic applications in order to replace conventional Silicon. In the third part of this report, we have investigated the electronic and dielectric properties of semiconducting layered Transition metal dichalcogenide materials (MX2)(M=Mo, W;X =S, Se, Te) which has recently emerged as a promising alternative to Si as channel materials for CMOS devices. Five layered MX2 materials(exceptWTe2)in their 2D sheet and 1D nanoribbon forms are considered to study the real and imaginary band structure of thoseMX2 materials by atomistic simulations. Studying the complex dispersion properties, it is shown that all the five MX2 support direct BTBT in their monolayer sheet forms and offer an average ON current and subthresholdslopeof150 A/mand4 mV/dec, respectively. However, onlytheMoTe2 support direct BTBT in its nanoribbon form, whereas the direct BTBT possibility in MoS2 and MoSe2 depends on the number of layers or applied uniaxial strain. WX2 nanoribbons are shown to be non-suitable for efficient TFET operation. Reasonably high tunneling current in these MX2 shows that these can take advantage over conventional Silicon in future tunnel field effect transistor applications.

Organic solar cells have great potential for cost-effective and large area electricity production, but their applicability is limited by the relatively low efficiency. In this dissertation I report investigations of novel materials and the underlying principles of organic solar cells, carried out at the University of St Andrews between 2011 and 2015. Key results of this investigation: • The charge carrier mobility of organic semiconductors in the active layer of polymer solar cells has a rather small influence on the power conversion efficiency. Cooling solar cells of the polymer:fullerene blend PTB7:PC₇₁BM from room temperature to 77 K decreased the hole mobility by a factor of thousand but the device efficiency only halved. • Subphthalocyanine molecules, which are commonly used as electron donor materials in vacuum-deposited active layers of organic solar cells, can, by a slight structural modification, also be used as efficient electron acceptor materials in solution-deposited active layers. Additionally these acceptors offer, compared to standard fullerene acceptors,advantages of a stronger light absorption at the peak of the solar spectrum. • A low band-gap polymer donor material requires a careful selection of the acceptor material in order to achieve efficient charge separation and a maximum open circuit voltage. • Metal structures in nanometer-size can efficiently enhance the electric field and light absorption in organic semiconductors by plasmonic resonance. The fluorescence of a P3HT polymer film above silver nanowires, separated by PEDOT:PSS, increased by factor of two. This could be clearly assigned to an enhanced absorption as the radiative transition of P3HT was identical beside the nanowires. • The use of a processing additive in the casting solution for the active layer of organic solar cells of PTB7:PC₇₁BM strongly influences the morphology, which leads not only to an optimum of charge separation but also to optimal charge collection.

Binary oxides constitute an outstanding class of functional materials with potential applications in many fields such as catalysis, gas sensing, field emission, solar cells, photodetection, etc. Due to the difference in their physical/chemical properties, different oxides have been explored for different applications. For examples, SnO2, Cr2O3 and ZnO are being explored for gas sensing due to their high adsorption capacity for volatile gases, ZnO, Cu2O etc. are being explored in solar cells because of high adsorption coefficient in UV/visible region and so on. Various techniques are available for synthesis of binary oxides and tuning their properties. Most of the physical or chemical synthesis techniques are expensive, need high cost instruments and produces hazardous chemical waste. We need a simple, cost effective and ecofriendly techniques for the synthesis of binary oxides. In present work, a simple and facile thermal oxidation strategy has been employed for the synthesis of various binary oxides (Cu2O, GeO2 and ZnO). For example, CuO nanorods are obtained when Cu is heated around ~ 500 oC, which then heated in Ar atmosphere to obtain a film of porous Cu2O. Similarly, GeO2 with different morphologies and green-luminescent ZnO are obtained by controlling the reaction parameters. These oxides have then been explored for various applications including white light phosphors, catalysis for the degradation of dyes and non-contact thermometry. Overall, we present a thermal oxidation strategy for the synthesis of various binary oxides and explore potential applications in various fields.

Orientador: Prof. Dr. Jeverson Teodoro Arantes Junior / Tese (doutorado) - Universidade Federal do ABC, Programa de Pós-Graduação em Nanociências e Materiais Avançados, Santo André, 2018. / Investigamos, sistematicamente, as propriedades estruturais e eletrônicas do óxido de zinco nanoporoso sob tração e compressão biaxial utilizando cálculos de primeiros princípios baseados na Teoria do Funcional da Densidade. O sistema apresenta uma alta concentração de nanoporos lineares orientados nas direções cristalográcas [0001] e [01-10], bem como um lme no nanoporoso. Para compressões maiores do que 4% com relação ao parâmetro de rede, foi observada uma distorção estrutural nas regiões menos densas do material poroso, mostrando uma tendência à mudança de fase localizada. O coe- ciente de Poisson calculado dos nanoporos orientados na direção [0001] foi negativo. Isto signica que quando o material poroso foi tracionado, expandiu-se transversalmente. Já quando comprimido, o material contraiuse na direção transversal. Os materiais que possuem esta característica são conhecidos como materiais auxéticos. Nossos resultados mostram que o valor do gap de energia foi modulado pelas deformações biaxiais com uma tendência oposta ao bulk. A densidade dos estados eletrônicos conrmou nossas observações. A tendência estrutural inversa da superfície dos nanoporos é o principal mecanismo para o comportamento inverso do gap sob compressão e tração. Dentro do nosso conhecimento, este é o primeiro reporte de um comportamento inverso do gap de energia de estruturas de ZnO sob compressão e tração biaxial. Nossos resultados sugerem que a nanoporosidade, conjuntamente com tra- ção e compressão biaxial, podem ser empregadas como um método dentro da engenharia de gap para customizar materiais funcionais que requerem controle da atividade eletrônica. / This work investigated, systematically, the structural and electronic properties of nanoporous zinc oxide, under biaxial strain, through rst-principles methods, based on total energy ab initio calculations using Density Functional Theory. The system was in a massive nanopore concentration regime. We studied linear pores in [0001] and [01-10] direction and a porous thin lm. Using a biaxial tension above 4% of the ZnO bulk lattice parameter, we observed a distortion resulting in a local phase change region in the material's structure. The calculated Poisson's coecient was negative for the [0001] pore. When stretched, they become thicker in the perpendicular direction to the applied force. These materials are known as auxetic. Our results show that the energy band gap value is tuned by the strain with an uncommon opposite trend related to the bulk. The density of electronic states conrmed the energy gap modulation. The structural inverse trend of nanopores surface is the principal mechanism for gap inverse behavior under compressive and tensile strain. From the best of our knowledge, this is the rst report about opposite Egap trend in strained nanopores. Our results suggest that nanoporosity and biaxial strain could be employed as a method within the band gap engineering for tailored functional matexi rials that require control of the electronic activity.

The work deals with the measurement of CV characteristics of photovoltaic cells and the consequent derivation of the free / bound charge in the volume. It also discusses factors that influence these measurements.

This work presents a 6.5-kV 1-kA SiC bipolar diode module for megawatt-range medium voltage converters. The study comprises a review of SiC devices and bipolar diodes, a description of the die and module technology, device characterization and modelling and benchmark of the device at converter level. The effects of current change rate, temperature variation, and different insulated-gate bipolar transistor (IGBT) modules for the switching cell, as well as parasitic oscillations are discussed. A comparison of the results with a commercial Si diode (6.5 kV and 1.2 kA) is included. The benchmark consists of an estimation of maximum converter output power, maximum switching frequency, losses and efficiency in a three level (3L) neutral point clamped (NPC) voltage-source converter (VSC) operating with SiC and Si diodes. The use of a model predictive control (MPC) algorithm to achieve higher efficiency levels is also discussed. The analysed diode module exhibits a very good performance regarding switching loss reduction, which allows an increase of at least 10 % in the output power of a 6-MVA converter. Alternatively, the switching frequency can be increased by 41 %.:1 Introduction 2 State of the art of SiC devices and medium-voltage diodes 2.1 Silicon carbide diodes and medium-voltage modules 2.2 Medium-voltage power diodes 3 Characterization of the SiC PiN diode module 37 3.1 Introduction 3.2 Experimental setup 3.3 Experimental results: static behaviour 3.4 Experimental results: switching behaviour 3.5 Comparison with 6.5-kV silicon diode 3.6 Oscillations in the SiC diode 3.7 Summary 4 Comparison at converter level 4.1 Introduction 4.2 Power device modelling 4.3 Determination of maximum converter power rating 4.4 Analysis 4.5 Increased efficiency through model predictive control 4.6 Summary 5 Conclusion

L’alliage germanium-étain est un semiconducteur qui suscite une grande attention en raison de ses propriétés électriques et optiques. L’incorporation de Sn dans le germanium permet d’ajuster la largeur de bande interdite (gap) et d’améliorer la mobilité des électrons et des trous, et pour une quantité suffisante d’étain, le matériau passe d’un gap indirect à direct. Cet alliage est versatile parce qu’il peut être intégré d’une façon monolithique sur le Si, c’est ce qui en fait un matériau idéal dans les domaines de l'optoélectronique à base de silicium. Cette thèse est sur la fabrication et la caractérisation de nanofils cristallins Ge1-xSnx à haute concentration en Sn. Des nouvelles stratégies ont été employées pour fabriquer de nombreux types de nanofils GeSn. Les résultats ont été expliqués en fonction des modèles cinétiques existants. Un nouveau mécanisme de croissance y est décrit: le mécanisme solide-solide-solide – SSS. Il consiste à faire croître des nanofils de GeSn dans le plan du substrat à l’aide de catalyseurs d’étain à une température inférieure au point de fusion de Sn. Quatre modèles de transport de masse sont proposés pour le mécanisme de croissance du SSS. Diverses caractérisations (par exemple TEM et APT) ont été effectuées pour étudier les propriétés physiques, et chimiques des nanofils. / Germanium-Tin alloy is a unique class semiconductor gaining a strong attention because of its significant electrical and optical properties. Sn incorporation in Ge allows straightforward band-gap engineering enabling to enhance the electron and hole mobilities, and for a sufficient Sn amount an indirect-to-direct band-gap transition occurs. Its versatility rises due the possible monolithic integration on Si-platforms making it an ideal material in domains of optoelectronics, and high speed electronic devices. This thesis has focused on the fabrication and characterization of crystalline Ge1-xSnx nanowires with high Sn concentrations. New strategies were designed to fabricate many types of GeSn nanowires. The results have been explained as function of the existing kinetic models. A new growth mechanism was reported (i.e. Solid-Solid-Solid mechanism – SSS), it consists of growing in-plane GeSn nanowires using Sn catalysts below the melting point of Sn. Four mass transport models were proposed for the SSS growth mechanism. Various characterizations (e.g. TEM and APT) were done to investigate the physical and chemical properties of the obtained nanowires.