Superconductivity and Tunneling Spectroscopy in Granular and Homogeneous Quench Condensed thin Films

1990 ◽  
Vol 195 ◽  
Author(s):  
J. M. Valles ◽  
R. C. Dynes
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Sheet Resistance ◽  
Long Range ◽  
Order Parameter ◽  
Energy Gap ◽  
Tunneling Spectroscopy ◽  
Phase Coherence ◽  
Granular Films ◽  
Grain Sizes

ABSTRACTQuench-condensed films of simple superconductors can be deposited with a morphology which is either granular (grain sizes on the scale of tens of angstroms) or homogeneous. Transport and tunneling studies of the normal and superconducting states of these films as a function of sheet resistance have revealed profound differences between them. In uniform films Tc. and the energy gap decrease continuously with decreasing film thickness. Superconductivity is destroyed by the reduction of the amplitude of the order parameter. In granular films, the grains are sufficiently large to support superconductivity in each grain. Long range phase coherence is destroyed by intergrain phase coherence breaking.

Structural, Optical, and Optoelectrical Studies of Spray Pyrolyzed CuGaSnS4 Thin Films

2021 ◽  
Author(s):  
Islam M El radaf ◽  
Hnan Y Alzahrani
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Nonlinear Optical ◽  
Energy Gap ◽  
Structural Parameters ◽  
Stoichiometric Composition ◽  
Optical Energy Gap ◽  
Linear Absorption ◽  
Glass Substrates ◽  
D Values

Abstract We deposited CuGaSnS4 thin films on soda-lima glass substrates via a spray pyrolysis process. The X-ray diffraction of CuGaSnS4 films established the formation of an orthorhombic single phase. In addition, the structural parameters of the CuGaSnS4 films were estimated by Debye-Scherer’s formulas, which showed that an enhancement in crystallite size (D) values occurred by increasing the thickness of the investigated films. The EDAX pattern of CuGaSnS4 films confirms a stoichiometric composition. The optical results revealed that the CuGaSnS4 films possessed a direct optical energy gap (Eg). The Eg values were reduced from 1.50 to 1.38 eV with the increase in thickness. Also, there was an observed increase in the linear refractive index and the linear absorption coefficient values occurred due to the increased thickness. Finally, the optoelectrical constants of the sprayed CuGaSnS4 films such as the optical conductivity (σopt) and the optical free carrier concentration to effective mass (N_opt/m^* ) were enlarged with increasing film thickness. The nonlinear optical study showed that the increase in film thickness enhanced the nonlinear optical constants of CuGaSnS4 films. The hot-probe procedure shows that the sprayed CuGaSnS4 films expose p-type conductivity.

scholarly journals Effect of thickness on the optical properties of ZnO thin films prepared by pulsed laser deposition technique (PLD)

2019 ◽  
Vol 15 (32) ◽  
pp. 114-121
Author(s):  
Maysar A. Salim
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Optical Properties ◽  
Film Thickness ◽  
Energy Gap ◽  
Transparent Conducting Oxide ◽  
Zno Thin Films ◽  
Zno Films ◽  
Zno Thin Film ◽  
Optical Energy Gap

Zinc Oxide (ZnO) thin films of different thickness were preparedon ultrasonically cleaned corning glass substrate, by pulsed laserdeposition technique (PLD) at room temperature. Since mostapplication of ZnO thin film are certainly related to its opticalproperties, so the optical properties of ZnO thin film in thewavelength range (300-1100) nm were studied, it was observed thatall ZnO films have high transmittance (˃ 80 %) in the wavelengthregion (400-1100) nm and it increase as the film thickness increase,using the optical transmittance to calculate optical energy gap (Egopt)show that (Egopt) of a direct allowed transition and its value nearlyconstant (~ 3.2 eV) for all film thickness (150, 180, 210, and 240)nm, so Zn0 thin films were used as a transparent conducting oxide(TCO) in various optoelectronic application such as a window in athin film solar cells.

Size Effects in BaTiO3 Thin Films

1995 ◽  
Vol 403 ◽  
Author(s):  
X. M. Lu ◽  
J. S. Zhu ◽  
P. Li ◽  
W. Jiang ◽  
X. Liu ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Curie Temperature ◽  
Film Thickness ◽  
Raman Spectra ◽  
Size Effects ◽  
Energy Gap ◽  
Optical Transmittance ◽  
Mechanical Dissipation

AbstractThe size effects were studied by the measurement of optical transmittance, Raman spectra and mechanical dissipation in BaTiO3 films. The variation of energy gap, Raman peaks, Curie temperature with film thickness and grain size was observed and the possible origin was analyzed.

The Investigations of Dielectric Properties of BaTiO3 Thin Films on Polycrystalline Pt Substrates by Rf Magnetron Sputtering

1996 ◽  
Vol 433 ◽  
Author(s):  
Jin Wook Jang ◽  
Woon Jo Cho ◽  
Taek Sang Hahn ◽  
Sang Sam Choi ◽  
Su Jin Chung
Keyword(s):  
Thin Films ◽  
Dielectric Properties ◽  
Magnetron Sputtering ◽  
Film Thickness ◽  
Room Temperature ◽  
Strong Dependence ◽  
Hysteresis Loops ◽  
Rf Magnetron Sputtering ◽  
Thickness Dependence ◽  
Grain Sizes

AbstractThickness dependence of ferroelectric and structural properties of BaTiO3 thin films were investigated. Stoichiometric BaTiO3 thin films were prepared by off-axis rf magnetron sputtering on polycrystalline Pt substrates at 700°C. Film thickness range was 2,100–20,000Å. Room temperature permittivity, frequency dependence of permittivity, and D-E hysteresis loops were measured and lattice parameters were determined as a function of the film thickness. It has been found that these properties had the strong dependence on film thickness, which was mainly due to grain sizes of BaTiO3 thin films. The main cause of thickness dependence of dielectric properties was thought to be crystallinity and stresses of thin films which is resulted from changes in grain sizes.

scholarly journals Influence of Film Thickness and Heat Treatment on the Physical Properties of Mn Doped Sb2Se3 Nanocrystalline Thin Films

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
I. K. El Zawawi ◽  
Manal A. Mahdy ◽  
E. A. El-Sayad
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Film Thickness ◽  
Energy Gap ◽  
Blue Shift ◽  
Amorphous Structure ◽  
Treatment Temperature ◽  
Optical Energy Gap ◽  
Heat Treated ◽  
Nanocrystalline Thin Films

Nanocrystalline thin films of Sb37.07Mn1.95Se60.98 with different thickness (7, 20, 40, and 80 nm) were successfully prepared via inert gas condensation technique. As-deposited films showed amorphous structure by grazing incident in-plane X-ray diffraction (GIIXD) technique. All films of different thicknesses were heat treated at 433 K for 90 min. The GIIXD pattern of annealed films showed nanocrystalline orthorhombic structure. The effect of thickness of annealed films on the structure and optical properties was studied. Calculated particle sizes are 20.67 and 24.15 for 40 and 80 nm thickness of heat treated film. High resolution transmission electron microscope HRTEM images and their diffraction patterns proved that 40 nm film thickness annealed at different temperature has nanocrystalline nature with observed (high) crystallinity that increases with annealing temperature. Blue shift of optical energy gap was observed from 1.68 to 2 eV with decreasing film thickness from 80 to 7 nm. Film thickness of 40 nm was exposed to different heat treated temperatures from 353 to 473 K to detect its effect on structure and optical and electrical properties. Blue shift from 1.73 to 1.9 eV was observed in its optical band gap due to direct transition as heat treatment temperature decreasing from 473 to 353 K. Electrical conductivity was studied for different heat treated films of thickness 40 nm, and intrinsic conduction mechanism is dominant. The activation energy Ea was affected by heat treatment process.

scholarly journals Impact of Thickness on the Optical Properties of Selenium Thin Films

2021 ◽  
Vol 25 ◽  
Author(s):  
Shiva Udachan ◽  
Narasimha Ayachit ◽  
Lingappa Udachan ◽  
Raghunanda Halembre
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Film Thickness ◽  
Band Gap ◽  
Optical Density ◽  
Energy Gap ◽  
Band Gap Energy ◽  
Primary Objective ◽  
Gap Energy ◽  
The Impact

Objectives: The primary objective of this investigation is to make a systematic study on the impact of thickness on optical properties, such as energy gap, absorption coefficient, optical density etc., for selenium thin films. Understanding of the band gap energy and its influence on film thickness is of utmost importance in acquiring the intended electrical characterization of semiconducting films. Materials and methods: Ultra-purity selenium (99.99 %) was deposited on glass substrates. During deposition, the glass substrate with its holder were rotated with constant speed to have a smooth coating. Results and discussions: The XRD findings indicate that selenium is amorphous in nature. The optical band gap energy is found to be decreasing form (2.3 to 2eV) with the rise of film thickness in interval (200 to 1000 nm). The band gap energy obeys inverse square law with respect to thickness. Conclusion: We have properly grown thin films of Se below the De Broglie wavelength limit by thermal evaporation in vacuum. The optical density varies directly with film thickness. The absorption coefficients were in the interval (0.5 to 4) × 107m-1. The AFM results confirmed that the Se nano-size increases with the increase in thickness. Both the grain boundaries and sub-grain regions are clearly visible in the SEM micrographs

Characterization of Rapid Thermal and Micro-Wave Annealed Germanium Thin Films Grown by E-Beam Evaporation on Glass Substrates

2013 ◽  
Vol 663 ◽  
pp. 431-435
Author(s):  
Li Te Tsou ◽  
Sheng Hao Chen ◽  
Huai Yi Chen ◽  
Yao Jen Lee ◽  
Horng Show Koo ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electron Beam ◽  
Film Thickness ◽  
Sheet Resistance ◽  
Cross Section ◽  
Rapid Thermal Annealing ◽  
Glass Substrates ◽  
Microwave Annealing

In this paper, we used the electron beam (e-beam) evaporation to deposit Ge thin film on glass, and used microwave annealing (MWA) system of 5.8 GHz frequency for thin film crystallization. Then, we compared the MWA experiment results of sample sheet resistance (Rs), crystallization strength and cross section with those using traditional rapid thermal annealing (RTA) equipment. We found that MWA can get poly-Ge thin film with (111), (220) and (311) crystallization directions and optimal Rs at a temperature of about 450 ° C without affecting the film thickness. By comparison, RTA equipment can only reduce the sample Rs at least temperature of 550oC.

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