A SIMPLE MODEL FOR OBTAINING OPTICAL CONSTANTS OF POROUS SILICON

2001 ◽  
Vol 15 (17n19) ◽  
pp. 745-748
Author(s):  
JAIME TORRES ◽  
JAIRO GIRALDO
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Simple Model ◽  
Porous Silicon ◽  
Optical Constants ◽  
Normal Incidence ◽  
Sample Thickness ◽  
Infinite Dimensions ◽  
Simple Method ◽  
Harmonic Oscillator Model

A simple method is proposed to calculate optical constants from porous silicon (PS) thin films, out of the simulation of normal incidence reflection spectrums. In the optical system used in this model, PS one considers as a homogeneous uniform thin film when deposited upon a substrate with semi-infinite dimensions. The PS and Substrate refractive indexes are obtained using the Simple Harmonic Oscillator Model, proposed by Wemple and DiDomenico. In addition, the absorption coefficient and sample thickness are also be obtained. The model to calculate the optical constants of some samples prepared at different anodisation times is used.

Thermochromic VO2 Thin Film Prepared by Post Annealing Treatment of V2O5 Thin Film

2009 ◽  
Vol 79-82 ◽  
pp. 747-750 ◽  
Author(s):  
Dong Qing Liu ◽  
Wen Wei Zheng ◽  
Hai Feng Cheng ◽  
Hai Tao Liu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Transition ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Annealing Treatment ◽  
Simple Method ◽  
X Ray ◽  
Post Annealing ◽  
Vo2 Thin Films

Thermochromic vanadium dioxide (VO2) exhibits a semi-conducting to metallic phase transition at about 68°C, involving strong variations in electrical and optical properties. A simple method was proposed to prepare VO2 thin films from easily gained V2O5 thin films. The detailed thermodynamic calculation was done and the results show that V2O5 will decompose to VO2 when the post annealing temperature reaches 550°C at the atmospheric pressure of less than 0.06Pa. The initial V2O5 films were prepared by sol-gel method on fused-quartz substrates. Different post annealing conditions were studied. The derived VO2 thin film samples were characterized using X-ray diffraction and X-ray photoelectron spectroscopy. The electrical resistance and infrared emissivity of VO2 thin films under different temperatures were measured. The results show that the VO2 thin film derived from the V2O5 thin film annealed at 550°C for 10 hours is pure dioxide of vanadium without other valences. It was observed that the resistance of VO2 thin film with thickness about 600nm can change by 4 orders of magnitude and the 7.5-14μm emissivity can change by 0.6 during the phase transition.

scholarly journals Secrets revealed — Spatially selective wetting of plasma-patterned periodic mesoporous organosilica

2012 ◽  
Vol 90 (12) ◽  
pp. 1063-1068
Author(s):  
Wendong Wang ◽  
Ian B. Burgess ◽  
Benjamin D. Hatton ◽  
Jack Alvarenga ◽  
Joanna Aizenberg
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Information Security ◽  
Oxygen Plasma ◽  
Periodic Mesoporous Organosilica ◽  
Simple Method ◽  
Wetting Properties ◽  
Mesoporous Organosilica ◽  
Selective Wetting

We report a simple method to pattern wetting properties on thin films of periodic mesoporous organosilica (PMO). A hydrophobic methane PMO thin film was covered by masks and exposed to oxygen plasma to make the unmasked area hydrophilic. The wettability patterns could be revealed only when the films were immersed in water or exposed to moisture. We expect that our method would extend the utility of PMO to such areas as sensing and information security.

scholarly journals Obliquely Bideposited TiN Thin Film with Morphology-Dependent Optical Properties

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1418
Author(s):  
Yi-Jun Jen ◽  
Wei-Chieh Ma ◽  
Ting-Yen Lin
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Extinction Coefficient ◽  
Normal Incidence ◽  
Columnar Structure ◽  
Index Of Refraction ◽  
Tin Film ◽  
Tin Thin Films ◽  
Visible Wavelengths ◽  
Incident Cases

TiN thin films were obliquely bideposited with different subdeposit thicknesses. The morphology of the bideposited film was varied from a nano-zigzag array to a vertically grown columnar structure by reducing the subdeposit thickness. The principal index of refraction and extinction coefficient were obtained to explain the measured reflectance and transmittance spectra. The loss of the bideposited thin film decreased as the thickness of the subdeposit decreased. The principal indices for normal incidence were near or under unity, indicating the low reflection by the bideposited thin films. A TiN film with a subdeposit thickness of 3 nm demonstrated an average index of refraction of 0.83 and extinction coefficient of below 0.2 for visible wavelengths. The retrieved principal refractive indexes explained the anisotropic transmission and reflection. For most normal incident cases, the analysis offers the tunable anisotropic property of a TiN nanostructured film for multilayer design in the future.

Modeling the Optical Quantum Efficiency of Thin Film Amorphous Silicon Solar Cells

2000 ◽  
Vol 609 ◽  
Author(s):  
Sally-anne F. Rowlands ◽  
John Livingstone ◽  
Christopher P. Lund
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Solar Cells ◽  
Amorphous Silicon ◽  
Quantum Efficiency ◽  
Indium Tin Oxide ◽  
Optical Constants ◽  
Spectral Response ◽  
Good Prediction ◽  
Transmission Spectra

ABSTRACTThe optical quantum efficiency and spectral response of p-i-n thin film amorphous silicon (a-Si:H) solar cells have been modeled using software based on optical admittance analysis. The optical constants of a-Si:H and Indium Tin Oxide (ITO) thin film layers have been measured by Variable Angle Spectroscopic Ellipsometry (VASE) and used as inputs into the optical admittance analysis program in order to model cells constructed from these films.Amorphous silicon thin films and p-i-n assemblies have been deposited by glow discharge and reactive sputtering techniques. The optical constants of doped and intrinsic a-Si:H thin films were determined by VASE and the film thickness verified by Scanning Electron Microscopy studies. The optical constants of commercially available transparent conducting oxide (TCO) coated substrates have also been determined by VASE.The experimental transmission spectra of p-i-n assemblies are compared with transmission spectra that have been modeled using the measured optical constants. Results of modeling different a-Si:H solar cell structures using these materials are presented, including a study of the optimal TCO layer thickness for p-i-n a-Si:H solar cells. This work shows that optical admittance modeling gives a good prediction of the optical behavior of p-i-n assemblies, but that accurate measurements of the optical constants of the component films are required in order to model effectively the optical quantum efficiency and photocurrent.

Optical Properties of RF-Sputtered a-SiGe:H:O Alloys

1986 ◽  
Vol 77 ◽  
Author(s):  
J. M. T. Pereira ◽  
P. K. Banerjee ◽  
S. S. Mitra
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Constants ◽  
Rf Sputtering ◽  
Normal Incidence ◽  
Reflection And Transmission ◽  
Amorphous Thin Films ◽  
Optical Gap ◽  
Transmission Measurements ◽  
Substrate Temperatures

ABSTRACTAmorphous thin films of SixGe1-x:O (x = 0.70) were prepared by RF-sputtering at several substrate temperatures. The structural properties of these films were studied by IR spectroscopy and revealed features characteristic of hydrogen and/or oxygen bonded to silicon. The optical constants (n,k) were determined from reflection and transmission measurements at near-normal incidence for photon energies in the range of 1 eV and 2.6 eV. The optical gap was derived from the Taue plot and correlated with the composition of the samples. The increase of hydrogen and/or oxygen decreases the value of the refractive index and increases the optical gap.

A Study on Fabricating Microdeep Recessed Part on Copper Foil Using Laser Indirect Shock Forming

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Huixia Liu ◽  
Zongbao Shen ◽  
Xiao Wang ◽  
Pin Li ◽  
Yang Hu ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Strain Distribution ◽  
Copper Foil ◽  
Laser Energy ◽  
Sample Thickness ◽  
Metallic Thin Films ◽  
Target Plate ◽  
Microfabrication Technique ◽  
Good Agreement

Laser indirect shock forming is a novel microfabrication technique to introduce 3D profiles in metallic thin films. Experiments were performed by allowing the laser-driven flyer to impact the thin film, which is placed above a micromould. The effects of laser energy and sample thickness on deformation mechanism were investigated experimentally. The experimental results show that increasing the laser energy could increase the deformation depth, but may induce fracture along the edges of the micromould when the laser energy is too high. Moreover, the target plate was completely sheared off for 10 μm copper when the pulse energy is 1200 mJ. So it can be found that the technique can also realize micro punching of metallic thin films. The transient deformation of copper foil impacted by laser-driven flyer is simulated in this paper. Experimental data obtained were then used to validate the corresponding simulation model. Good agreement has been obtained between the numerical simulation and the experiments under different laser energy. The rising temperature due to the adiabatic conditions is taken into account. And the strain distribution has been also calculated numerically.

CALCULATION OF OPTICAL CONSTANTS IN POROUS SILICON THIN FILMS USING DIFFUSED AND SPECULAR REFLECTANCE MEASUREMENT

2002 ◽  
Vol 09 (05n06) ◽  
pp. 1821-1825 ◽  
Author(s):  
C. PEÑA ◽  
J. TORRES
Keyword(s):  
Thin Films ◽  
Porous Silicon ◽  
Optical Constants ◽  
Refraction Index ◽  
Summation Method ◽  
Electrochemical Anodization ◽  
Reflectance Measurement ◽  
Theoretical Simulation ◽  
Specular Reflectance ◽  
Two Samples

In this work a method is proposed to calculate the optical constants of porous silicon (PS) thin films. The method is based on the theoretical simulation of the experimental reflectance spectra. In the optical system of this method the PS is considered a homogeneous, absorbing thin film, deposited on a silicon substrate of semi-infinite dimension. The theoretical form of the systems reflectance is calculated using the summation method proposed by Airy. Light scattering is included in the model by introducing the Davies–Bennett relation. The refraction index of the material is fit with the simple harmonic oscillator, proposed by Wemple–DiDomenico. The model was tested on two samples fabricated with anodization times of 25 and 35 min; the values for the refraction indexes, absorption coefficients, thickness and roughness were calculated for both samples. The PS samples were fabricated by electrochemical anodization of single crystal p-type silicon substrates in HF (25%) + isopropyl alcohol solution.

A Rapid Method to Measure Thermal Conductivity of Dielectric Thin Films: Thermal Resistance Method

2005 ◽  
Author(s):  
Da-Jeng Yao ◽  
Heng-Chieh Chien ◽  
Ming-Hsi Tseng
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Dielectric Film ◽  
Electrical Heating ◽  
New Technique ◽  
Simple Method ◽  
Dielectric Thin Films ◽  
Resistance Method

A new and relatively simple method, described for thermal conductivity measurement of dielectric thin films, is presented in this paper. This new technique, the thermal resistance method, can be applied to determine cross-plane thermal conductivity of thin film by electrical heating and sensing techniques without traditional free standing structure design. A slender metal line, deposited on top of dielectric film, is used to measure and extract thermal resistance (Rc) of composite structure, including substrate and dielectric film. A 2-D analytical solution is derived to get thermal resistance (Rs) of substrate. Therefore, the thermal resistance of thin film (Rf) is calculated by subtracting Rs form Rc and thermal conductivity of thin film can also be extracted from thermal resistance. The measurement data of silicon dioxide with difference thickness are verified by using previous scientific literatures. In addition, the measuring results also show good agreement with those measured by 3 omega method. According to advantages of rather rapid and accuracy, this new technique has potential to develop to be an in-line test key for MEMS and IC relative industries.

Extraction of Elastic Modulus and Hardness of the Soft Metallic Films on Hard Substrates by Nanoindentation

2007 ◽  
Vol 561-565 ◽  
pp. 2005-2008
Author(s):  
X.Y. Zhou ◽  
Hai Rong Wang ◽  
Zhuang De Jiang ◽  
Rui Xia Yu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Elastic Modulus ◽  
Contact Stiffness ◽  
Cross Sectional ◽  
Simple Method ◽  
Sem Image ◽  
Sputter Deposited ◽  
Film Substrate ◽  
Hard Substrates

A simple method to extract the intrinsic mechanical properties of the soft metallic thin films on hard substrates by nanoindenation is presented. Utilizing the geometry relationship of residual impressions obtained by the SEM image and the cross-sectional profile, the pile up error in elastic modulus determination of soft thin films by the Oliver and Pharr analysis is first corrected. Knowledge of the ‘true’ elastic modulus, the ‘true’ hardness of thin film is then extracted from the measured contact stiffness data for an elastically homogeneous film-substrate system. The present method is applied for a 504 nm Au thin film sputter deposited on the glass substrate and the results show that the ‘true’ elastic modulus and hardness of Au film are 80 GPa and 1.3 GPa, which are in agreement well with the literatures.

A simple method to determine the optical constants and thicknesses of ZnxCd1−xS thin films

1996 ◽  
Vol 289 (1-2) ◽  
pp. 238-241 ◽  
Author(s):  
J Torres ◽  
J.I Cisneros ◽  
G Gordillo ◽  
F Alvarez
Keyword(s):  
Thin Films ◽  
Optical Constants ◽  
Simple Method
Sign in / Sign up

Export Citation Format

Share Document