A simple spectrophotometric method for determination of the optical constants and band gap energy of multiple layer TiO2 thin films

Sreemany, Monjoy; Sen, Shrabanee

doi:10.1016/j.matchemphys.2003.09.030

Cited by 141 publications

(69 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In this case, the absorption coefficient "a" is determined through the natural logarithm of the transmittance. When (ahn) n is plotted against the incident photon energy (hn), a linear relationship is obtained only when n = 2, which is consistent with a direct band gap semiconductor 35 . The above is shown in Figure 8, where an optical band gap (straight line interception with hn axis) of 2.04 eV was achieved.…”

Section: Film Characterizationsupporting

confidence: 52%

EFFECT OF CHLORIDE IONS ON THE STRUCTURAL, OPTICAL, MORPHOLOGICAL, AND ELECTROCHEMICAL PROPERTIES OF Cu2O FILMS ELECTRODEPOSITED ON FLUORINE-DOPED TIN OXIDE SUBSTRATE FROM A DMSO SOLUTION

Riveros

León

Ramírez

2016

J. Chil. Chem. Soc.

View full text Add to dashboard Cite

This study shows the results attained during the electrodeposition of Cu 2 O films on fluorine-doped tin oxide (FTO) substrate from a dimethyl sulfoxide (DMSO) solution in the presence of chloride ions. Before the film electrodeposition and in order to establish the best conditions for the Cu 2 O electrodeposition, a detailed electrochemical study of the precursors in the presence of chloride ions was performed. The voltammetric profiles obtained show significant differences compared to those previously obtained during the study of the Cu 2 O electrodeposition from a free-chloride DMSO solution. These differences are the result of the coordination complexes formation between chloride ions and the different copper species in solution. The films were potentiostatically electrodeposited between -1.4 V and -1.6 V vs Ag/AgCl (sat) reference electrode. Then, these films were characterized through different techniques: X-ray diffraction, scanning electron microscopy, optical characterization, and capacitance measurements through electrochemical impedance spectroscopy.Keywords: Cu 2 O, Electrodeposition, DMSO solution, Chloride effect. INTRODUCTIONPhotovoltaic devices based on metal oxide semiconductors have being a matter of great interest, because to their chemical stability. This way, due to its properties (p-type semiconductor, direct band gap of 2.0 -2.2 eV) Cu 2 O has been considered an excellent material that can be employed in photovoltaic cells based on p-n junction thin films. Furthermore, Cu 2 O is made up of abundant non-toxic elements, which allows it to become a low-cost material 1 .Cu 2 O thin films have been prepared through the use of different techniques such as magnetron sputtering 2-3 , chemical vapor deposition 4-5 , thermal oxidation 6 , and chemical reduction 7 . Electrochemical techniques are easy and inexpensive methods for Cu 2 O thin films formation. Copper sulfate in the presence of lactic acid / lactate aqueous solution is usually the most used electrolyte for the electrodeposition of Cu 2 O thin film on different substrates [8][9][10] . However, this research group has recently verified that the electrodeposition of Cu 2 O thin films can be carried out from a dimethyl sulfoxide (DMSO) solution, using CuClO 4 and molecular oxygen as precursors 11 . These films were p-type semiconductors with an optical band gap that varied between 2.18 eV -2.25 eV with a doping level between 8.2 x 10 18 cm -3 -2.0 x 10 19 cm -3 , depending on the electrodeposition temperature. On the other hand, it is a well known fact that during the electrodeposition process, the addition of complexing agents produces drastic changes in the morphology and properties of semiconductor materials 12-13 and metals [14][15] . This way, the influence of chloride ions as a complexing agent during the Cu 2 O electrodeposition process from a DMSO solution is analyzed in this article. The results were then compared with those obtained in the absence of chloride ions. The films were smoother than those obtained in the absence ...

show abstract

Section: Film Characterizationsupporting

confidence: 52%

EFFECT OF CHLORIDE IONS ON THE STRUCTURAL, OPTICAL, MORPHOLOGICAL, AND ELECTROCHEMICAL PROPERTIES OF Cu2O FILMS ELECTRODEPOSITED ON FLUORINE-DOPED TIN OXIDE SUBSTRATE FROM A DMSO SOLUTION

Riveros

León

Ramírez

2016

J. Chil. Chem. Soc.

View full text Add to dashboard Cite

show abstract

“…We should note, however, that variations in 20% have been measured for TiO 2 films prepared by sol-gel. 59 Once the sample thickness reaches ϳ100 nm, the observed pale yellow color is characteristic of TiO 2 . 6,60 A complete analysis of the optical properties of these films is currently being investigated and will be reported elsewhere.…”

Section: Discussionmentioning

confidence: 99%

A comprehensive study of the influence of the stoichiometry on the physical properties of TiOx films prepared by ion beam deposition

Marchi

Bilmes

Ribeiro³

et al. 2010

Journal of Applied Physics

View full text Add to dashboard Cite

Articles you may be interested inA comprehensive study of nonstoichiometry titanium oxide thin films ͑TiO x , 0.3Յ x Յ 2͒ prepared by ion beam deposition technique is reported. The physical properties of the material are studied by ultraviolet and x-ray photoelectron, Raman, and Fourier transform infrared spectroscopies, and atomic force microscopy. An abrupt transition from metallic characteristics to a wide gap semiconductor is observed in a very narrow range of oxygen variation. Concomitantly with this change the crystal structure and morphology suffer remarkable physical properties modifications. This transformation is ascribed to surface-volume energy minimization due to the influence of oxygen determining the size of the TiO 2 particles during coalescence.

show abstract

“…Os parâmetros ópticos 7,27 (índice de refração; porosidade), espessura do filme e energia de band gap 28 foram determinados a partir dos espectros de transmitância obtidos na faixa do UV-Vis (espectrofotômetro Varian Cary 50).…”

Section: Caracterização Dos Filmes Nanoestruturados De Tiounclassified

“…Observa-se a presença da fase cristalina anatase caracterizada pela reflexão em 2θ ≈ 25° correspondente ao plano cristalino [101] e do halo na região 20°<2θ<40° correspondente à parte amorfa do substrato de vidro. 27 (Tabela 1). Na preparação em que se empregou o HCl não houve influência do tempo de envelhecimento no tamanho de cristalito estimado, que variou de 29 a 32 nm.…”

Section: Caracterização Dos Filmes Nanoestruturados De Tiounclassified

“…27 A energia de band gap (Eg) para transição direta permitida 28 foi calculada a partir da extrapolação de (ahn) 2 = 0 do gráfico (ahn) 2 x hn, sendo a e n obtidos do espectro de transmitância dos filmes finos na região do UV-VIS. Os valores calculados para os parâmetros ópticos e Eg dos filmes feitos a partir de HAc e HCl são apresentados na Tabela 1.…”

Section: Caracterização Dos Filmes Nanoestruturados De Tiounclassified

See 1 more Smart Citation

Influência do tipo de ácido e tempo de envelhecimento na atividade fotocatalítica de filmes finos de TiO2

Nakamura¹,

Vaz²

2011

Quím. Nova

View full text Add to dashboard Cite

Recebido em 18/10/10; aceito em 28/1/11; publicado na web em 15/4/11 TYPE OF ACID AND AGEING EFFECT INFLUENCE ON PHOTOCATALYTIC ACTIVITY OF TiO 2 THIN FILMS. TiO 2 thin films were prepared by the sol-gel method using different acids (HCl and HAc), with a parallel evaluation of the gel ageing effects on the film properties. After the thermal treatments, the resulting materials were characterized through gravimetric analysis, UV-VIS spectrophotometry (from which optical parameters such as band gap was derived), XRD, morphological surface analysis (AFM) and photocatalytic activity. The majority of the obtained thin films parameters were similar independent of the acid type and the ageing time of the gel. Nevertheless, a visible effect of the surface morphology properties on the films and their photocatalytic activity was observed.Keywords: titanium dioxide; sol-gel; photocatalysis. INTRODUÇÃOO crescimento industrial e doméstico não sustentável está intrinsecamente ligado ao aumento da emissão de poluentes, o que consiste em um dos mais sérios problemas mundiais da atualidade. Infelizmente, tal condição tende a se agravar gradualmente, uma vez que o descarte dos poluentes no meio ambiente ocorre, em sua grande parte, in natura. Além disso, a pequena fração de poluentes submetida a processos de tratamento nem sempre é corretamente eliminada, devido à ineficiência da maioria dos métodos convencionais utilizados. Em virtude deste inconveniente e da crescente conscientização ambiental, órgãos competentes vêm trabalhando e criando normas e legislações cada vez mais rigorosas, de modo a minimizar tal problema. [1][2][3][4] Os tratamentos convencionais baseiam-se na transferência de fase dos poluentes sem, contudo, destruí-los ou convertê-los em substân-cias menos nocivas. Um exemplo são as estações de tratamento de esgoto, em que há a geração do lodo em que estão concentrados os poluentes. 5,6 Por isso, pesquisas nas mais diversas áreas do conhecimento são atualmente realizadas com o objetivo de aperfeiçoar e desenvolver novas tecnologias mais eficazes.Um processo promissor para o tratamento de poluentes e purificação de água e ar é a fotocatálise heterogênea, a qual integra os processos oxidativos avançados (POA).7 Este processo fotocatalítico é baseado na iluminação de um material semicondutor com radiação de energia maior ou igual à sua energia de band gap, correspondente à quantidade de energia necessária para excitar um elétron da banda de valência (BV) e promovê-lo para a banda de condução (BC). Com a promoção do elétron para a BC, ocorre a separação de cargas formando o par lacuna/elétron (h + /e -) com potencial de oxidação e/ou redução suficiente para a degradação dos compostos orgânicos. 1,8-12A grande vantagem da fotocatálise heterogênea sobre os demais métodos de tratamento utilizados atualmente é que consegue promover a mineralização completa dos compostos orgânicos, evitando assim a produção de rejeitos. Isto significa que um composto pode ser mineralizado completamente, obtendo-se como produtos finais dióxi...

show abstract

A simple spectrophotometric method for determination of the optical constants and band gap energy of multiple layer TiO2 thin films

Cited by 141 publications

References 22 publications

EFFECT OF CHLORIDE IONS ON THE STRUCTURAL, OPTICAL, MORPHOLOGICAL, AND ELECTROCHEMICAL PROPERTIES OF Cu2O FILMS ELECTRODEPOSITED ON FLUORINE-DOPED TIN OXIDE SUBSTRATE FROM A DMSO SOLUTION

EFFECT OF CHLORIDE IONS ON THE STRUCTURAL, OPTICAL, MORPHOLOGICAL, AND ELECTROCHEMICAL PROPERTIES OF Cu2O FILMS ELECTRODEPOSITED ON FLUORINE-DOPED TIN OXIDE SUBSTRATE FROM A DMSO SOLUTION

A comprehensive study of the influence of the stoichiometry on the physical properties of TiOx films prepared by ion beam deposition

Influência do tipo de ácido e tempo de envelhecimento na atividade fotocatalítica de filmes finos de TiO2

Contact Info

Product

Resources

About