In this study, InSe and CdS thin films were deposited by thermal evaporation method onto glass substrates. Schottky and heterojunction devices were fabricated by deposition of InSe and CdS thin films onto SnO2 coated glass substrates with various top metal contacts such as Ag, Au, In, Al and C. The structural, electrical and optical properties of the films were investigated prior to characterization of the fabricated devices. The structural properties of the deposited InSe and CdS thin films were examined through SEM and EDXA analysis. XRD and electrical measurements have indicated that undoped InSe thin films deposited on cold substrates were amorphous with p-type conductivity lying in the range of 10-4-10-5 (&amp / #61527 / .cm)-1 at room temperature. Cd doping and post-depositional annealing effect on the samples were investigated and it was observed that annealing at 100 oC did not show any significant effect on the film properties, whereas the conductivity of the samples increased as the Cd content increases. Temperature dependent I-V and Hall effect measurements have shown that conductivity and carrier concentration increases with increasing absolute temperature while mobility is almost temperature independent in the studied temperature range of 100-430 K. The structural and electrical analysis on the as-grown CdS thin films have shown that the films were polycrystalline with n-type conductivity. Temperature dependent conductivity and Hall effect measurements have indicated that conductivity, mobility and carrier concentrations increases with increasing temperature. Transmission measurements on the as-grown InSe and CdS films revealed optical band gaps around 1.74 and 2.36 eV, respectively. Schottky diode structures in the form of TO/p-InSe/Metal were fabricated with a contact area of around 8x10-3 cm2 and characterized. The best rectifying devices obtained with Ag contacts while diodes with Au contacts have shown slight rectification. The ideality factor and barrier height of the best rectifying structure were determined to be 2.0 and 0.7 eV, respectively. Illuminated I-V measurements revealed open-circuit voltages around 300 mV with short circuit current 3.2x10-7 A. High series resistance effect was observed for the structure which was found to be around 588 &amp / #61527 / . Validity of SCLC mechanism for Schottky structures was also investigated and it was found that the mechanism was related with the bulk of InSe itself. Heterostructures were obtained in the form of TO/n-CdS/p-InSe/Metal and the devices with Au and C contacts have shown the best photovoltaic response with open circuit voltage around 400 mV and short circuit current 4.9x10-8 A. The ideality factor of the cells was found to be around 2.5. High series resistance effect was also observed for the heterojunction devices and the fill factors were determined to be around 0.4 which explains low efficiencies observed for the devices.

In this work, we will focus on the quaternary system Cu1-xAgxInSe2 (CAIS) to investigate the effects of silver (Ag) contribution and exchange with copper (Cu) in CuInSe2. This system is located between the ternary semiconducting chalcopyrite compounds CuInSe2 and AgInSe2. These are two most popular materials applied in photovoltaic cells because of their high optical absorption coefficient, which is an important factor for the manufacture of devices, direct energy gap with values Eg ~1.05 and 1.24 eV, respectively, and excellent thermal stabilities in air. As being a quaternary alloy, we expect that Cu1-xAgxInSe2 will show the advantage of a large degree of variation of their properties as a function of the composition, which allows adjusting of the band gap and other properties. We will analyze the behavior of Ag in the structure depending on the annealing and the effects of the Ag exchange to the Cu vacancies in this crystal structure by changing x (Ag content). The crystals will be characterized structurally by X-ray diffraction (XRD). It will be used to prove crystallinity, determine perfection and lattice parameters depending on composition. Surface morphology and stoichiometry will be examined using scanning electron microscope (SEM) equipped with EDXA. Moreover, electrical properties including the temperature dependent electrical conductivity, and carrier concentrations and mobility extracted from Hall effect measurements, and, optical properties including absorption coefficient, photoconductivity, spectral transmission, and optical band gap have been determined to characterize Cu1-xAgxInSe2 thin films deposited using e-beam evaporation technique.

Polyvinyl alcohol (PVA) desize effluent is a high COD contributor to towel manufacturing plant's Primary Oxygenation Treatment of Water operation, and being non-biodegradable, is a threat to the environment. When all-PVA/wax size is used in weaving, significant incentives exist to recover the synthetic polymer material from the desize wash water stream and reuse it. A new technology that would eliminate the disadvantages of the current Reverse Osmosis Ultrafiltration (UF) PVA recovery process is Vacuum Flash Evaporation (VFE). This research adapts the VFE process to the recovery and reuse of all-PVA size emanating from towel manufacturing, and compares the economics of its implementation in a model plant to current plant systems that use PVA/starch blend sizes with no materials/water recovery. After bench scale research optimized the VFE PVA recovery process from the desize effluent and determined the mass of virgin PVA that was required to be added to the final, recycled PVA size formulations. The physical changes in the recycled size film and yarn composite properties from those of the initial (conventional) slashing were determined using a number of characterization techniques, including DSC, TGA, SEM, tensile testing, viscometry, number of abrasion cycles to first yarn breaks, microscopy and contact angle measurements. Cotton chemical impurities extracted from the yarns during desizing played an important role in the recovered PVA film physical properties. The recovered PVA improved the slashed yarn weave ability. Along with recovered PVA, pure hot water was recovered from the VFE. Virgin wax adds to the final, recycled size formulations were determined to be unnecessary, as the impurities extracted into the desize effluent stream performed the same functions in the size as the wax. Using the bench results, the overall VFE process was optimized and demonstrated to be technically viable through six cycles, proof-of-concept trials conducted on a Webtex Continuous Pilot Slasher. Based on the pilot scale trials, comparative economics were developed. Incorporation of the VFE technology for PVA size recovery and recycling resulted in ~$3.2M/year in savings over the conventional PVA/starch/wax process, yielding a raw ROI of less than one year based on a $3M turnkey capital investment.

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2007. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Mémoire (Sc. A.)--Université du Québec à Chicoutimi, 1987. / Bibliogr: ff. 114-118. Document électronique également accessible en format PDF. CaQCU

Thesis (Ph.D.)--Aerospace Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Seitzman, Jerry; Committee Member: Jagoda, Jechiel; Committee Member: Lieuwen, Tim; Committee Member: Menon, Suresh; Committee Member: Tan, David.

Made available in DSpace on 2014-06-11T19:23:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-18Bitstream added on 2014-06-13T19:09:17Z : No. of bitstreams: 1 macieljunior_jlb_me_bauru.pdf: 1682253 bytes, checksum: a84fdbae9148badab55fa6a6aa5a53c3 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A proposta deste trabalho é a investigação das propriedades elétricas e ópticas de filmes finos de dióxido de estanho (Sn'O IND. 2') obtidos via sol-gel e por solução alcoólica depositados via dip-coating, e, filmes de alumina ('Al IND. 2''O IND. 3') obtidos por deposição de filmes de alumínio (Al) via evaporação resistiva e tratamento térmico em diferentes ambientes, para promover a oxidação de Al. A investigação individual quanto às propriedades ópticas e elétricas desses materiais conhecer seu comportamento na forma de filmes, e estudar a região interfacial de Sn'O IND. 2' e 'Al IND. 2''O IND. 3'. As caracterizações estruturais dos filmes foram feitas por difração de raios-X (DRX), e, no caso dos filmes de alumina, utilizou-se também microscopia eletrônica de varredura (MEV) e microscopia óptica. Nas caracterizações ópticas foram utilizadas técnicas de espectroscopia na região do ultravioleta e no infravermelho próximo (UV-Vis-Nir). Tanto os filmes obtidos por meio alcoólico como obtidos via SGDC foram caracterizados como sendo de Sn'O IND. 2' de estrutura tetragonal do tipo rutilo, sendo que os filmes obtidos via processo alcoólico apresentaram condutividade elétrica maior do que os filmes obtidos via SGDC. Os resultados referentes aos filmes finos de alumínio indicam que independentemente da quantidade de camadas de alumínio depositadas e da atmosfera de tratamento térmico, tem-se a oxidação do alumínio à alumina ('Al IND. 2''O IND. 3'), sendo que a estrutura dominante depende da atmosfera de tratamento. A sua utilização como camada isolante no gate em dispositivo metal-óxido-semicondutor é viável, pois a corrente fonte-dreno apresenta valores significativamente maiores do que a corrente fonte-gate. / The main goal of this work is the investigation of properties of tin dioxide (Sn'O IND. 2') and alumina ('Al IND. 2''O IND. 3) thin films. The first one was obtained through the sol-gel process as well as alcoholic solution, via dip-coating. The alumina thin films were obtained by resistive evaporation of aluminum (Al) followed by thermal annealing in distinct atmospheres, to promote the Al oxidation. The individual investigation of optical and electrical properties of these materials aims the knowledge of their behavior as thin films, which allows studying the interface layer of the heterojunction Sn'O IND. 2' e 'Al IND. 2''O IND. 3'. Structural characterization of films was carried out by X-ray diffraction (XRD) technique and particularly on the alumina films, scanning electron microscopy (SEM) and optical microscopy were done. For the optical characterization, wide spectra were obtained, with spectroscopy from ultraviolet to near infrared (UV-Vis-Nir). Either the films obtained in the alcoholic solution as well as via SGDC, where characterized as Sn'O IND. 2' of tetragonal structure of rutile type, and the films obtained through alcoholic process present electrical conductivity higher than the films obtained via SGDC. Results on aluminum thin films indicate that independent on the amount of deposited aluminum and thermal annealing atmosphere, the oxidation of aluminum to alumina ('Al IND. 2''O IND. 3) takes place, but the dominant alumina structure depends on the thermal annealing atmosphere. Besides, its utilization as insulating layer at the gate of a metal-oxide semicondutor device is achievable, because the source-drain current is significantly higher than the source-gate current.

Made available in DSpace on 2014-06-11T19:23:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-08-19Bitstream added on 2014-06-13T20:30:16Z : No. of bitstreams: 1 correa_p_me_bauru.pdf: 1146240 bytes, checksum: a8f40673e6edfa69035f9c03a71c97da (MD5) / Neste trabalho é feita a deposição de filmes finos pela técnica de Evaporação Resistiva a partir de pós de Arseneto de Gálio (GaAs) e compostos de GaAs com Óxidos e Cloretos de Érbio (Er) ou Itérbio (Yb). Trata-se de um método relativamente simples de deposição, no qual os compostos são evaporados conjuntamente. O objetivo é observar a eficiência desse método para a produção desses filmes finos, a partir de compostos que possuam diferentes características, tais como consideráveis diferenças de temperaturas de evaporação. Depositamos filmes em diferentes condições e estequiometrias e analisamos as propriedades estruturais pela técnica de difração de raios-X. A composição qualitativa das amostras foi obtida por energia dispersiva de raios-X. As propriedades ópticas foram analisadas através de medidas de transmitância óptica dentro da faixa do visível ao infravermelho médio. Realizamos também a caracterização elétrica através de medidas de resistência em função da temperatura em filmes de GaAs e composto de GaAs com 'ErCl IND 3'. Apresentamos no apêndice uma proposta de investigação das propriedades de transporte elétrico de uma dessas amostras, envolvendo um modelo para cálculo da condutividade. De imediato, a contribuição deste trabalho é para a compreensão dos fenômenos físicos que acontecem durante o processo de crescimento, e a investigação parâmetros de deposição que viabilizem o emprego da técnica para os diferentes materiais evaporados. / In this work, thin film deposition is carried out, using the resistive evaporation technique, from powders of gallium arsenide (GaAs) and erbium (Er) or ytterbium (Yb) oxides and chlorides. It is a relatively simple deposition technique, where the compounds are simultaneously evaporated. The goal is to observe the efficiency of this growth method for the production of thin films, from compounds with distinct characteristics, such as high difference between evaporation temperatures. Films have been deposited under different conditions and stoichiometry, and their structural properties were analyzed by X-ray diffraction technique. Sample composition was obtained by X-ray dispersive energy. Optical properties were analyzed through optical transmittance from visible to medium infrared. Electrical characterization was also carried out, using measurements of resistance as function of temperature for GaAs and GaAs with 'ErCl IND 3' compounds. An appendix is also presented, containing a proposal of electrical transport investigation, involving conductivity calculation. The contribution of this work is towards the understanding of physical phenomena that takes place during the growth process, and the investigation of deposition parameters with make reliable the utilization of this technique for the different evaporated materials.

Ce manuscrit présente des études expérimentales sur l'évaporation de gouttes et la chimiotaxie de la mite.Une première partie s'intéresse à l'évaporation de spray dense au moyen d'une nouvelle approche, par analogie avec le mélange scalaire. Dans cette limite de forte densité en gouttes, où il y a saturation en vapeur au sein des structures constituantes, l'évaporation est principalement fonction de l'étirement auxquelles ces structures sont soumises. C'est en effet celui-ci qui conditionne le taux d'évacuation de cette vapeur interstitielle, ce qui permet de mettre les gouttes en contact avec un environnement plus sec, déclenchant ainsi leurs évaporations.Une deuxième partie s'intéresse à une application de la compréhension de cette dynamique d'évaporation de spray dense à un contexte d'entomologie: la chimiotaxie de la mite. Il s'agit du processus par lequel l'animal va se repérer dans un champ de concentration, pour localiser la source d'une substance attractive par exemple (ici de la phéromone sexuelle). Cette partie a tendu vers l'obtention d'une visualisation conjointe de la trajectoire de l'animal et du champ de concentration sous-jacent par la visualisation des gouttes. / This thesis present some experiments on droplets evaporation and moth chemotaxis.In a first part, dense spray evaporation is explained through a new approach, drawing an analogy with scalar mixing. In this high density droplets limit, where vapor saturation is reached within the structures, evaporation is mainly controlled by the intensity at which these structures are stretch. It is indeed the stretching that controls the rate at witch interstitial vapor is evacuated: droplets are thus in contact with a dryer environment, so they can start to evaporate.A second part take an interest in applying dense spray evaporation dynamic understanding to an entomologist situation: moth chemotaxis. This is the process by which animals find their way in a concentration field, such at finding a chemoattractant source for instance (sexual pheromone in our case). This part tended towards visualizing animal trajectory and concentration field underlying through droplets visualization simultaneously.