In this study , we investigate the relationship between growth condition and thin film quality of cadmium sulfide (CdS) thin films grown by chemical bath deposition (CBD) method. Thin film structures are analyzed by X-ray diffraction , morphology and grain size are obtained by scanning electronic microscopy , and film thickness measured by reflectance spectroscopy . In medium pH value ( pH=10.5) , 20 min deposition can achieve 450 nm film thickness . At lower pH (pH=8.5), low hydrolysis rate of thiourea limits the concentration of sulfur anion , film thickness is only 49 nm after one hour deposition at 70 ¢J , and the obtained thin film can not fully cover the substrate to have a pin-hole free film . At higher pH (pH=11), 40 min only deposites 100 nm film thickness. Strong binding between the cadmium ion and the complexing agent causes low free cadmium cation concentration in the solution, which limits the growing rate. By varying the growth pH condition, the difference in thickness is more than one order of magnitude. In contrast to the film thickness relationship, grain size distribution suffers less influence from the pH consition. Our results indicate no explicitly relation between the grain size and solution pH condition. 20 minutes depositions result cadmium sulfide grain sizes to be 70¡Ó10nm , and 40 minutes result grain size to be 75¡Ó15nm . The results indicate that film thickness increases mainly due to the increasing of grain number, rather than the increasing of grain size . By summarized the results, we propose that the deposition of cadmium sulfide film is initially formed homogeneous nucleation in the solution. The nuclea diffuse and adhere to the substrate. Intristic electric dipole momentum of the cadmium sulfide nano-particle provides an attractive force for the adhesion, and results preferred orientation. Meanwhile, the grain keeps growing up until the size saturated .

Made available in DSpace on 2014-06-11T19:25:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-06-26Bitstream added on 2014-06-13T20:14:10Z : No. of bitstreams: 1 amseijunior_nl_me_ilha.pdf: 2699114 bytes, checksum: c6abbb8f07f024d65eb10a3cef381405 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Preparou-se e caracterizou-se, neste trabalho, semicondutores de PbS (Chumbo Sulfide) e Bi2S3 (Bismuto Sulfide) através do método de Deposição por Banho Químico (CBD). Este método tem provado ser o método mais barato e também não poluente. A técnica consistiu na preparação de solução de íons metálicos misturada em uma solução que contenha o íon S-2 formar o semicondutor na forma de filme fino e precipitado (pó). Semicondutor de PbS foi preparado misturando, em temperatura ambiente, solução de acetato de chumbo, hidróxido de sódio, tiouréia e trietanolamina (TEA). Por outro lado, semicondutor de Bi2S3 foi preparado misturando, em temperatura ambiente, solução de nitrato de bismuto, tioacetamida e trietanolamina. A medida de difração de Raios-X (XRD) mostrou a uma estrutura cúbica de face centrada de PbS e uma estrutura ortorrômbica de Bi2S3, que além de formar os semicondutores, mostrou indícios de impureza (sulfate e hidroxidos) em tratamento térmico acima de 200ºC. Pela medida de Calorimetria Diferencial de Varredura, (DSC) dos pós dos semicondutores, o dado mostrou que para PbS a temperatura de cristalização está em torno de 350ºC e para Bi2S3 está em torno de 273ºC com formações de outras fases. Medidas de Transmitância Uv-Vis-Nir foram usadas para determinar os gaps ópticos para os filmes finos semicondutores. Considerando as transições diretas e indiretas, os valores dos gaps para os filmes finos de PbS estiveram em torno de 0,5 eV e para os filmes finos de Bi2S3 em torno de 1,6 eV, mudando com o tratamento térmico. A medida Espectroscopia Fotoelétria de Raios-X (XPS) foi usada para mostrar a evolução de crescimento dos semicondutores nos filmes. Na medida elétrica, a resistência diminuiu com o aumento da temperatura, mostrando o comportamento típico dos semicondutores. / In this work, we prepared and characterized PbS (Lead Sulfide) and Bi2S3 (Bismuth Sulfide) semiconductors by Chemical Bath Deposition (CBD) method. This method has been proved to be the least expensive and non-polluting method. The technique consisted in the preparation of metallic ions solution mixed in a solution that contains the S-2 ion to form the semiconductor in the thin film and precipitated (powder) forms. PbS semiconductor was prepared by mixing, at room temperature, of lead acetate, sodium hydroxide, thiourea, and triethanolamine (TEA) solutions. On the other hand, Bi2S3 semiconductor was prepared by mixing, at room temperature, of bismuth nitrate, thioacetamide, and triethanolamine solutions. The X-ray diffraction (XRD) measure showed a PbS face centered cubic structure and a Bi2S3 orthorhombic structure that besides forming the semiconductors, there were indications of impurity (sulfate and hydroxide) in thermal treatment above 200ºC. By the measure of Differential Scanning Calorimetric (DSC) of the semiconductor powders, data has shown that for PbS the crystallization temperature is about 350ºC and for Bi2S3 is about 273ºC with other phase formations. Uv-Vis-Nir transmittance measures were used to determine the optical gaps for the semiconductor thin films. Considering direct and indirect transition, the gap values for PbS thin films are about 0.5 eV and for Bi2S3 thin films are about 1.6 eV, changing with the thermal treatment. The X-ray Photoelectric Spectroscopy (XPS) measure was used to show the semiconductor growth evolution in the films. In the electrical measure, the resistance decreased with the increase of the temperature, showing the typical behavior of the semiconductors.

The buffer layer is a crucial component in thin film solar cells. Defects at the interface between absorber and buffer layer lead to high recombination rate and the band structure at the interface highly affects the performance of the solar cell. In this thesis a method to synthesize thin films containing cadmium, zinc and sulfur, CdZnS, by chemical bath deposition has been developed and evaluated. A higher current from the device is expected when replacing the common buffer layer cadmium sulfide, CdS, with the more transparent CdZnS. It is also possible that the alternative buffer provides a more favorable energy band alignment at the interface with the absorber Copper-Zinc-Tin-Sulfide (CZTS). The deposition process was developed by studying depositions on glass. Increasing [Zn2+]/[Cd2+] initially led to films with higher band gap (Eg). By varying deposition time the time before colloidal growth became dominant was observed. Addition of triethanolamine showed that triethanolamine binds stronger to zinc ions than to cadmium ions. Two recipes that led to Eg=2.63 eV were evaluated as buffer layer in Copper-Indium-Gallium-Selenide (CIGSe) and CZTS solar cells. The short circuit current of the devices increased in general with the CdZnS buffers compared to CdS. The best CZTS cell with a CdZnS buffer layer had 7.7 % efficiency compared to the 7.5 % reference. For future research it is recommended that the effect of thickness variation and deposition temperature is evaluated and that additional material characterization is performed in order to further understand and develop the deposition method.

Le sulfure de zinc est l'un des premiers semiconducteurs découverts. Il a un grand potentiel d’applications grâces à ses propriétés physicochimiques. Il est intensément utilisé dans des applications optoélectroniques, photocatalytiques et pour la détection de gaz. En particulier, il est utilisé pour des applications photovoltaïques. Dans ce contexte, nous avons commencé par l’étude de l’effet du dopage par des métaux de transition (manganèse, cobalt et cuivre) sur les propriétés structurales, microstructurales, morphologiques, optiques, électriques et magnétiques des couches minces de sulfure de zinc préparées par la technique de dépôt chimique en solution (chemical bath deposition (CBD)) par diffraction aux rayons X, spectroscopie photoélectronique X, spectroscopie Raman, spectroscopie infrarouge, microscopie électronique à balayage, spectrophotométrie UV-Vis-NIR, effet Hall et SQUID. En second lieu nous avons étudié l’effet de la variation de l’épaisseur des couches formant la cellule photovoltaïque à base de Cu(In,Ga)Se2 par la simulation numérique à deux dimensions sous éclairement AM1.5 de puissance 100 mW/cm2 effectué sous Silvaco ATLAS / Zinc sulfide is one of the first semiconductors discovered. It has great potential application thanks to its physicochemical properties. It is used extensively in optoelectronic, photocatalytic and gas detection applications. In particular, it is used for photovoltaic applications. In this work, the effect of doping by transition metals (manganese, cobalt and copper) on the structural, microstructural, morphological, optical, electrical and magnetic properties of zinc sulfide thin films prepared by chemical bath deposition (CBD) technique are studied by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, infrared spectroscopy, scanning electron microscopy, UV-VIS-NIR spectrophotometry, Hall effect and SQUID. The modeling and optimization of higher efficiency Cu(In,Ga)Se2 solar cells are also investigated in this thesis for various layers thickness by using Silvaco ATLAS

NEVES, Wellington de Queiroz. Caracterização ótica e estrutural de filmes de CdS depositados por banho químico. 2013. 79 f. Dissertação (Mestrado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2013. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-10-23T18:58:00Z No. of bitstreams: 1 2013_dis_wqneves.pdf: 2637234 bytes, checksum: abe116493230fe2c301fd4d61f25b006 (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-10-23T19:37:34Z (GMT) No. of bitstreams: 1 2013_dis_wqneves.pdf: 2637234 bytes, checksum: abe116493230fe2c301fd4d61f25b006 (MD5) / Made available in DSpace on 2015-10-23T19:37:34Z (GMT). No. of bitstreams: 1 2013_dis_wqneves.pdf: 2637234 bytes, checksum: abe116493230fe2c301fd4d61f25b006 (MD5) Previous issue date: 2013 / Neste trabalho estudamos as propriedades óticas de filmes de sulfeto de cádmio (CdS) crescidos sobre um substrato de vidro. Os filmes foram obtidos por meio da técnica de deposição por banho químico (Chemical Bath Deposition, CBD). Os filmes de CdS são preparados numa solução aquosa, sob agitação, a uma temperatura de 80 oC durante 60 minutos sobre substrato de vidro. Alguns dos filmes foram obtidos com duplo depósito em dois banhos sucessivos iguais. Como fonte de íons de cádmio é usado sulfato de cádmio (CdSO4,) como fonte de íons de enxofre é usado a tioureia, como tampão é usado cloreto de amônia, e como agente complexante o Ethylenediamine tetra acetic acid (Edta) em várias concentrações. Após o crescimento, os filmes foram submetidos a um tratamento térmico no ar nas temperaturas de 300 ou 400 oC por uma hora. Foram realizadas medidas experimentais usando a técnicas de difração de raios-X, fototransmissão ótica UV-VIS e espectroscopia Raman. Os filmes de CdS obtidos possuem estrutura cúbica e são de coloração amarelada, homogêneos e muito aderentes ao substrato de vidro. São analisados os efeitos da concentração de Edta, tratamento térmico no ar, tempo de deposição e temperatura de crescimento dos filmes de CdS. Nossos resultados mostram que, sob as condições estudadas, os filmes de CdS não possuem fase hexagonal em sua estrutura. O gap dos filmes de CdS está em torno de 2,45 eV, com pequenas variações (2,40 – 2,51 eV) devido às condições experimentais de crescimento ou tratamento térmico após o crescimento. Observamos o modo LO, de simetria A1, em torno de 300 cm-1 e até três sobremodos desse fônon. Em alguns casos, os espectros Raman aparecem sobre uma larga fotoemissão, dependendo das condições experimentais.

Orientador: Victor Ciro Solano Reynoso / Banca: José Humberto Dias da Silva / Banca: Luiz Francisco Malmonge / Resumo: Preparou-se e caracterizou-se, neste trabalho, semicondutores de PbS (Chumbo Sulfide) e Bi2S3 (Bismuto Sulfide) através do método de Deposição por Banho Químico (CBD). Este método tem provado ser o método mais barato e também não poluente. A técnica consistiu na preparação de solução de íons metálicos misturada em uma solução que contenha o íon S-2 formar o semicondutor na forma de filme fino e precipitado (pó). Semicondutor de PbS foi preparado misturando, em temperatura ambiente, solução de acetato de chumbo, hidróxido de sódio, tiouréia e trietanolamina (TEA). Por outro lado, semicondutor de Bi2S3 foi preparado misturando, em temperatura ambiente, solução de nitrato de bismuto, tioacetamida e trietanolamina. A medida de difração de Raios-X (XRD) mostrou a uma estrutura cúbica de face centrada de PbS e uma estrutura ortorrômbica de Bi2S3, que além de formar os semicondutores, mostrou indícios de impureza (sulfate e hidroxidos) em tratamento térmico acima de 200ºC. Pela medida de Calorimetria Diferencial de Varredura, (DSC) dos pós dos semicondutores, o dado mostrou que para PbS a temperatura de cristalização está em torno de 350ºC e para Bi2S3 está em torno de 273ºC com formações de outras fases. Medidas de Transmitância Uv-Vis-Nir foram usadas para determinar os "gaps" ópticos para os filmes finos semicondutores. Considerando as transições diretas e indiretas, os valores dos "gaps" para os filmes finos de PbS estiveram em torno de 0,5 eV e para os filmes finos de Bi2S3 em torno de 1,6 eV, mudando com o tratamento térmico. A medida Espectroscopia Fotoelétria de Raios-X (XPS) foi usada para mostrar a evolução de crescimento dos semicondutores nos filmes. Na medida elétrica, a resistência diminuiu com o aumento da temperatura, mostrando o comportamento típico dos semicondutores. / Abstract: In this work, we prepared and characterized PbS (Lead Sulfide) and Bi2S3 (Bismuth Sulfide) semiconductors by Chemical Bath Deposition (CBD) method. This method has been proved to be the least expensive and non-polluting method. The technique consisted in the preparation of metallic ions solution mixed in a solution that contains the S-2 ion to form the semiconductor in the thin film and precipitated (powder) forms. PbS semiconductor was prepared by mixing, at room temperature, of lead acetate, sodium hydroxide, thiourea, and triethanolamine (TEA) solutions. On the other hand, Bi2S3 semiconductor was prepared by mixing, at room temperature, of bismuth nitrate, thioacetamide, and triethanolamine solutions. The X-ray diffraction (XRD) measure showed a PbS face centered cubic structure and a Bi2S3 orthorhombic structure that besides forming the semiconductors, there were indications of impurity (sulfate and hydroxide) in thermal treatment above 200ºC. By the measure of Differential Scanning Calorimetric (DSC) of the semiconductor powders, data has shown that for PbS the crystallization temperature is about 350ºC and for Bi2S3 is about 273ºC with other phase formations. Uv-Vis-Nir transmittance measures were used to determine the optical gaps for the semiconductor thin films. Considering direct and indirect transition, the gap values for PbS thin films are about 0.5 eV and for Bi2S3 thin films are about 1.6 eV, changing with the thermal treatment. The X-ray Photoelectric Spectroscopy (XPS) measure was used to show the semiconductor growth evolution in the films. In the electrical measure, the resistance decreased with the increase of the temperature, showing the typical behavior of the semiconductors. / Mestre

Ce travail s'inscrit dans le cadre de la recherche d'une amélioration des conditions de réalisation des dispositifs photovoltaïques à base du matériau semiconducteur ternaire CuInS2, qui doit constituer la couche absorbante dans la cellule solaire. Différentes techniques économiquement rentables ont été retenues pour l'élaboration de ce matériau : nous avons sélectionné le dépôt chimique en solution (CBD), la pulvérisation chimique réactive avec air (spray) et la pulvérisation chimique réactive sans air (PSA). Les matériaux élaborés ont été inclus dans des dispositifs photovoltaïques, pour lesquels le CuInS2 est réalisé soit avec la méthode PSA (CuInS2/ZnO/SnO2/verre ou CuInS2/In2S3/ZnO/SnO2/verre), soit avec la méthode de spray (CuInS2/In2S3:Al/SnO2/pyrex ou CuInS2/ZnS:In/SnO2/pyrex).Globalement, les propriétés structurales, morphologiques et optiques sont satisfaisantes. Pour les cellules incluant le CuInS2 déposé par spray, le photo-courant existe et atteint jusqu'à 200 µA dans le cas de la cellule CuInS2/ZnS:In/SnO2/pyrex, ou environ 4 A/cm2. / Photovoltaic solar cells based on I–III–VI2 ternary chalcopyrite absorber layers, have been the focus of intense investigation for over two decades. The use of chalcopyrite absorbers are highly appealing since their bandgaps correlate well to the maximum photon power density in the solar spectrum. Cu-chalcopyrite semiconductors have been studied extensively in recent years due to their applications as absorbers for large-area low-cost photovoltaic devices. CuInS2 as a chalcopyrite-semiconductor material has a direct band gap of 1.5 eV, a high absorption coefficient and nontoxic constituents and is, therefore, a promising candidate for photovoltaic applications. Different methods have been used to prepare CuInS2 films. Among these methods, spray pyrolysis, used in the present study, is an attractive one because large-area films with good uniformity may be prepared at low cost.

No description available.

Carbon nanotubes have been of great interest given their unique electronic and mechanical properties. Scholars have focused on the addition of carbon nanotubes to various matrices in order to develop novel materials. These new hybrid materials would combine the properties of both the nanotubes and the matrix of choice, which can both enhance the mechanical and electronic properties of the matrix material, and allow for the matrix to be used for other applications. In order to take advantage of the properties of the nanotubes, it is vital for them to be well dispersed in a solution or matrix as individual tubes, rather than as bundles. Additionally, it is cost effective to have individually dispersed tubes in a matrix. In order to individually disperse the tubes in the matrix, they can be pre-treated or functionalized via both covalent and non covalent processes. Subsequent to functionalization, the nanotubes can be coated with the matrix material or other metal compounds. This can help with the dispersion and interface interaction with the matrix material, or create materials with novel properties. This thesis focuses on conditions of growing various metal compounds or metal oxides on nanotubes using chemical bath deposition (CBD) and liquid phase deposition (LPD) methods. CBD and LPD use aqueous mediums for growth and deposition of compounds, which makes it both environmentally friendly and cost effective. Different pre-treatments are first employed on the nanotubes in order for them to be both well dispersed in solution and provide nucleation sites for the deposition and growth of various metal and metal oxides on the surface of the nanotubes. Once an ideal deposition is achieved, applications of the coated tubes are studied, tested and discussed.

Thin film solar cells of Copper Indium Telluride and Cadmium Sulfide junctions were fabricated on plain ITO glass slides and also on those coated with intrinsic Tin Oxide. CdS was deposited through chemical bath deposition and CIT by electrodeposition. Both compounds were subjected to annealing at temperatures between 350°C and 500°C which produced more uniform film thicknesses and larger grain sizes. The CIT/ CdS junction was characterized after performing XRD and spectral absorption of individual compounds. Studies were also made on CdS / CdTe solar cells with respect to effect of annealing temperatures on open circuit voltages. NP acid etch, the most important process to make the surface of CdTe tellurium rich, was also studied in terms of open circuit voltages. Thermally evaporated CdS of four different thicknesses was deposited on Tin Oxide coated ITO and inferences were drawn as to what thickness of CdS yields better results.