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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 4 (1984), S. 68-78 
    ISSN: 0392-6737
    Keywords: Optical properties of thin films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Mediante la misura dei valori di transmittanza e di riflettanza per lunghezze d'onda comprese fra 0.25 μm e 3 μm, sono state studiate le proprietà ottiche di film sottili (trasparenti e conduttivi) di SnO2 non drogato, preparati mediante sputtering. Dai valori così ottenuti sono stati ricavati valori del gap diretto dell'ordine di 4 eV e di quello indiretto dell'ordine di 3 eV. Un film di SnO2 presenta tipicamente valori della transmittanza intorno all'85%, per luce visibile,R ∂ intorno ai (100÷800) Ω∂ e resistività fra 2.4·10−3 e 1.8·10−2 Ω cm.
    Abstract: Резюме Пзмеряя величины пропускания и отражения в области длин волн между λ=0.25 мкм и λ=3 мкм, исследуются оптические свойства проводящих прозрачных тонких пленок нелегированного SnO2, приготовленных с помощью напыления. Из полученных оптических постоянных извлекаются значения прямой щели, порядка 4 эВ, и непрямой щели, порядка 3 эВ. Типичные пленки SnO2 пропускают ∼85% видимого света, имеют сопротивлениеR ∂ (100÷800) Ω∂ и удельные сопротивления в области (2.4·10−3÷1.8·10−2) Ом·см.
    Notes: Summary The optical properties of conductive transparent thin films of undoped SnO2, prepared by using magnetron supttering, were studied by measuring the transmittance and the reflectance between λ=0.25 μm and λ=3μm. The extracted optical constants are interpreted to give values of a direct band gap of the order of 4 eV and of an indirect band gap of the order of 3 eV. Typical SnO2 films transmit ≈85% of visible light, have sheet resistanceR ∂ (100÷800) Ω∂ and resistivities of (2.4·10−3÷1.8·10−2) Ω cm.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 8 (1986), S. 447-463 
    ISSN: 0392-6737
    Keywords: Photoconduction and photovoltaic effects ; photodielectric effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto In questo lavoro si presenta un modello per la determinazione e l'ottimizzazione dei parametri fondamentali atti a definire la qualità delle celle solari amorfe, specificando le proprietà ottiche, elettriche e di ricombinazione. Esso può essere applicato a qualunque sistema di celle solari amorfe. Sono fornite le espressioni teoriche ed è descritto un metodo iterativo per il calcolo numerico della densità di corrente di alcuni tipi di celle. Sono anche presentati i risultati ottenuti da calcoli eseguiti col computer e basati su questo modello.
    Notes: Summary A model for determination and optimization of the fundamental parameters defining the quality of amorphous solar cells in which optical, electrical and recombination properties are specified is developed. It can be applied to any amorphous solar-cell systems. This paper gives theoretical expressions and describes an iterative method of numerical calculation for the current density of different cells. Results of computer calculations based on this model are presented.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 9 (1987), S. 393-408 
    ISSN: 0392-6737
    Keywords: Electronic properties of specific thin films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Sono stati realizzati film dia-SiC:H mediante glow-discharge in atmosfera Ar-SiH4-CH4 con differenti rapporti CH4/SiH4. La concentrazione di H nei film è stata determinate usando la reazione di risonanza1H(15N, αγ)12C ed il contenuto di carbonio mediante spettrometria Rutherford-backscattering. Da misure di trasmittanza e riflettanza nella zona UV-visibile-vicino IR sono state ricavate le costanti ottiche, l'indice di rifrazione, la costante dielettrica, il coefficiente di assorbimento e il gap ottico. Un esame delle bande degli spettri vibrazionali dei vari legami CH, CSi e SiH ottenuti mediante misure di trasmissione nell'IR ha fornito un'interpretazione sulla struttura dei film. Sono state anche realizzate misure di conduttività di buio e di fotoconduttività sotto illuminamento di 500 W/m2. I risultati indicano che all'aumentare del contenuto di carbonio l'indice di rifrazione diminuisce sistematicamente per tutte le lunghezze d'onda, il gap ottico aumenta, la conduttività di buio diminuisce e nella configurazione strutturale tendono a prevalere le catene contenenti il carbonio.
    Abstract: Резюме Ъыли осаждены две системы пленокa-SiC:H в атмосфере Ar-SiH4-CH4, чтобы исследовать переменного отношения CH4/SiH4 на физические свойства. Состав пленок определяется с помощью резонансных ядерных реакций и измерений обратного резерфордовского рассеяния. Также определяются оптичззкся щеяь и показатель преломления с помщяю иемерений пронисаемости в видимойультрафиолетовой-близкой инфракрасной области, конфигурацуя связи с помощью измерений инфракрасной проницаемости и удельное сопротивление и фотопроводимость с помошью єлектрических измерений в темноте м при освешении 500 Bt/M2. Полученные результаты покасывают, что с увеличением содержания углерода показатель преомления систематически уменьшается для всех длин волн, єнергетическая щель увеличивается, темновое сопротивление увеличивается, конфигурация связи становится доминирующей за счет углерод-содержащих цепочек и структура становится более разориентировнной.
    Notes: Summary Two sets ofa-SiC:H films were deposited by glow discharge in an Ar-SiH4-CH4 atmosphere to investigate the effect of a variable CH4/SiH4 ratio on the physical properties. The composition of the films was determined by resonant nuclear reaction and by Rutherford backscattering measurements, the optical gap and the index of refraction by transmissivity measurements in the visible-UV-NIR range, the bonding configuration by IR transmissivity measurements and the resistivity and the photo-conductivity by electrical measurements in the dark and under a 500 W/m2 illumination. Results indicate that with increasing carbon content the refractive index decreases systematically over all wavelengths, the energy gap increases, the dark resistivity increases, the bonding configuration becomes dominated by carbon-containing chains and the structure more disordered.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 13 (1991), S. 795-800 
    ISSN: 0392-6737
    Keywords: Noise processes and phenomena
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary Measurements of photoinduced current noise in amorphous silicon solar cells are reported. A 1/f n (n≈1) component, superimposed to a frequency-independent one due to simple shot noise, is attributed to the presence of defects limiting the conversion efficiency of the cell. In particular, large defects, such as local shorts or pin holes, can easily be detected since they are characterized by a very large increase of the 1/f n component. In general, even in the absence of such large defects, a correlation between the intensity of the 1/f n component and the cell conversion efficiency is found.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 721-726 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The a-CSiSn alloy produced by rf magnetron sputtering in SiH4, CH4, and Ar atmosphere was studied as a function of the substrate temperature. The composition of the films was determined by elastic recoil detection analysis and by Rutherford backscattering measurements, and the density was then deduced. Results of a study of optical and electrical properties and of the bonding and structure of the films indicate that with the increase of the substrate temperature, the density and the imaginary part of the dielectric constant increases, the optical gap decreases, and the dark conductivity presents a different conduction mechanism depending on the substrate temperature. A correlation between the results obtained from nuclear measurements and IR spectroscopy is presented.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 611-618 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A detailed study of the optical properties of sputtered hydrogenated amorphous silicon films with varying hydrogen concentration is presented here. The energy dependence of the absorption coefficient is looked into, in detail, from a point of view of understanding the well known Tauc rule and the alternate relations being proposed in recent years. Spectroscopic and band-structural models like Wemple–Didomenico and Penn are then utilized to analyze the optical parameters near the band-gap region of the wavelength spectra. Extensive comparisons of our results are made with those of sputtered a-Si:H films of other workers, glow discharge prepared a-Si:H, chemically vapor deposited and evaporated a-Si, and also crystalline silicon. The similarities in the variation of the optical properties of a-Si:H with increasing hydrogen concentration (or decreasing measurement temperature) to that of crystalline silicon with decreasing measurement temperature lead us to interesting conclusions. Thus, it seems that decreasing disorder (topological or thermal) in a-Si:H is equivalent to decreasing thermal disorder in c-Si, at least as far as the disorder-optical property relationships are concerned.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 1155-1165 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The present study is focused on the vibrational and structural characterization of a set of disordered hydrogenated carbon nitride (a-CN:H) thin films grown by reactive sputtering. A comparative analysis of the experimental results as achieved by Raman and infrared (IR) spectroscopies is made. The disorder-induced features of IR and Raman spectra are discussed as well in light of the current assessment on the vibrational properties of carbon-based materials. Some differences between a-CN:H and nonnitrogenated a-C:H materials are evidenced and attributed to the effects of charge redistribution and bond polarization due to the presence of nitrogen. In order to justify such a hypothesis, the dielectric constant, the dynamic effective charge, and the IR cross section determined by the charge transfer effects are calculated and found to be in agreement with the corresponding experimental values. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 5424-5427 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optical properties of undoped α-Si:H films prepared using magnetron sputtering at different deposition conditions were studied by measuring their transmittance and reflectance between λ=0.25 and λ=1.5 μm and their thickness. The extracted optical constants are interpreted to give values of the band gap. Values of dark conductivity and activation energy are also obtained. The study has been extended to structures SnO2/α-Si:H/substrate. From measurements of transmittance and reflectance of the system optical constants of the components can be extracted.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 3650-3652 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A decreasing trend of the optical gap E04 with increasing sp2 carbon content has been noticed in amorphous carbon thin films. This behavior is common to materials grown using different deposition methods and having different composition and local structure. The use of a model of density of states in which the π bands are assumed to be Gaussian shaped allows us to explain such behavior, once the role of network distortion and hydrogen content in determining the width of the bands is taken into account. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 2520-2522 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The density of states in the energy region near Fermi level for hydrogenated amorphous carbon thin films is presented. The different types of states are identified in their origin and the problem of their detection is considered. It is shown that only some of these states are accessible to detection by electron spin resonance. A quantitative correlation between their density and the quantum efficiency of the room temperature photoluminescence process is achieved. Such correlation applies to films having a wide range of physical properties deposited by different techniques. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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