scholarly journals The Effect Of Thickness on The Optical Properties Of ZnS

2007 ◽  
Vol 4 (4) ◽  
pp. 647-652
Author(s):  
Baghdad Science Journal
Keyword(s):  
Band Gap ◽  
Room Temperature ◽  
Near Infrared ◽  
High Vacuum ◽  
Ultra Violet ◽  
Infrared Region ◽  
Complex Dielectric Constant ◽  
Film Properties ◽  
Corning Glass ◽  
Different Thickness

Zinc sulfide(ZnS) thin films of different thickness were deposited on corning glass with the substrate kept at room temperature and high vacuum using thermal evaporation technique.the film properties investigated include their absorbance/transmittance/reflectance spectra,band gap,refractive index,extinction coefficient,complex dielectric constant and thickness.The films were found to exhibt high transmittance(59-98%) ,low absorbance and low reflectance in the visible/near infrared region up to 900 nm..However, the absorbance of the films were found to be high in the ultra violet region with peak around 360 nm.The thickness(using optical interference fringes method) of various films thichness(100,200,300,and 400) nm.The band gap measured was found to be in the range (3.52 -3.78 )eV.

scholarly journals Temperature-dependent optical and vibrational properties of PtSe2 thin films

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Desman P. Gulo ◽  
Han Yeh ◽  
Wen-Hao Chang ◽  
Hsiang-Lin Liu
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Room Temperature ◽  
Near Infrared ◽  
Technological Development ◽  
Phonon Modes ◽  
Research Attention ◽  
Practical Applications ◽  
Infrared Frequency Range ◽  
Indirect Band Gap

Abstract PtSe2 has received substantial research attention because of its intriguing physical properties and potential practical applications. In this paper, we investigated the optical properties of bilayer and multilayer PtSe2 thin films through spectroscopic ellipsometry over a spectral range of 0.73–6.42 eV and at temperatures between 4.5 and 500 K. At room temperature, the spectra of refractive index exhibited several anomalous dispersion features below 1000 nm and approached a constant value in the near-infrared frequency range. The thermo-optic coefficients of bilayer and multilayer PtSe2 thin films were (4.31 ± 0.04) × 10−4/K and (–9.20 ± 0.03) × 10−4/K at a wavelength of 1200 nm. Analysis of the optical absorption spectrum at room temperature confirmed that bilayer PtSe2 thin films had an indirect band gap of approximately 0.75 ± 0.01 eV, whereas multilayer PtSe2 thin films exhibited semimetal behavior. The band gap of bilayer PtSe2 thin films increased to 0.83 ± 0.01 eV at 4.5 K because of the suppression of electron–phonon interactions. Furthermore, the frequency shifts of Raman-active Eg and A1g phonon modes of both thin films in the temperature range between 10 and 500 K accorded with the predictions of the anharmonic model. These results provide basic information for the technological development of PtSe2-based optoelectronic and photonic devices at various temperatures.

Pulsed Laser Deposition of Poly(Tetrafluoroethylene) Films

1995 ◽  
Vol 397 ◽  
Author(s):  
D.L. Kjendal ◽  
Ashok Kumar ◽  
R.B. Inturi ◽  
J. A. Barnard
Keyword(s):  
Pulsed Laser Deposition ◽  
Room Temperature ◽  
High Vacuum ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Deposition Technique ◽  
Nano Indentation ◽  
Corning Glass ◽  
Deposition Parameters ◽  
Compositional Properties

ABSTRACTThin films of poly(tetrafluoroethylene) have been deposited on amorphous (7059 Corning Glass) and silicon(l00) substrates at various temperatures by the Pulsed Laser Deposition technique. The deposition was carried out at high vacuum (˜10-6 torr)at temperatures ranging from room temperature to 350°C. The mechanical properties of these films at the varying process temperatures have been evaluated by nano-indentation techniques and compositional properties of the films have been characterized by Fourier Transform Infrared spectroscopy. The deposition parameters have been optimized in order to produce good quality films.

scholarly journals Формирование аморфных нанокластеров и нанокристаллов германия в пленках GeSi-=SUB=-x-=/SUB=-O-=SUB=-y-=/SUB=- на кварцевой подложке с использованием печных и импульсных лазерных отжигов

2020 ◽  
Vol 54 (3) ◽  
pp. 251
Author(s):  
Zhang Fan ◽  
С.А. Кочубей ◽  
M. Stoffel ◽  
H. Rinnert ◽  
M. Vergnat ◽  
...  
Keyword(s):  
Raman Spectra ◽  
Absorption Edge ◽  
Near Infrared ◽  
Laser Annealing ◽  
High Vacuum ◽  
Infrared Region ◽  
Fused Silica ◽  
Silica Substrate ◽  
Germanium Nanocrystals ◽  
Germanium Clusters

Abstract Nonstoichiometric GeO_0.5[SiO_2]_0.5 and GeO_0.5[SiO]_0.5 germanosilicate glassy films are produced by the high-vacuum coevaporation of GeO_2 and either SiO or SiO_2 powders with deposition onto a cold fused silica substrate. Then the films are subjected to furnace or laser annealing (a XeCl laser, λ = 308 nm, pulse duration of 15 ns). The properties of the samples are studied by transmittance and reflectance spectroscopy, Raman spectroscopy, and photoluminescence spectroscopy. As shown by analysis of the Raman spectra, the GeO[SiO] film deposited at a substrate temperature of 100°C contains amorphous Ge clusters, whereas no signal from Ge–Ge bond vibrations is observed in the Raman spectra of the GeO[SiO_2] film deposited at the same temperature. The optical absorption edge of the as-deposited GeO[SiO_2] film corresponds to ~400 nm; at the same time, in the GeO[SiO] film, absorption is observed right up to the near-infrared region, which is apparently due to absorption in Ge clusters. Annealing induces a shift of the absorption edge to longer wavelengths. After annealing of the GeO[SiO_2] film at 450°C, amorphous germanium clusters are detected in the film, and after annealing at 550°C as well as after pulsed laser annealing, germanium nanocrystals are detected. The crystallization of amorphous Ge nanoclusters in the GeO[SiO] film requires annealing at a temperature of 680°C. In this case, the size of Ge nanoclusters in this film are smaller than that in the GeO[SiO_2] film. It is not possible to crystallize Ge clusters in the GeO[SiO] film. It seems obvious that the smaller the semiconductor nanoclusters in an insulating matrix, the more difficult it is to crystallize them. In the low-temperature photoluminescence spectra of the annealed films, signals caused by either defects or Ge clusters are detected.

scholarly journals Broadband photoluminescence in a ceramic (Mg2SnO4–SnO2):Cr3+ system

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
N. D. C. Santana ◽  
A. López ◽  
L. P. Sosman ◽  
S. S. Pedro
Keyword(s):  
Room Temperature ◽  
Near Infrared ◽  
Electronic Configuration ◽  
Infrared Region ◽  
Spectroscopic Studies ◽  
Crystal Field Theory ◽  
X Ray ◽  
Broadband Light Source ◽  
Near Infrared Region ◽  
Intense Emission

AbstractThis study reports the synthesis and photoluminescence spectroscopic studies of Cr3+-doped Mg2SnO4–SnO2 ceramics. The crystal structure was analyzed by X-ray powder diffraction, and photoluminescence was investigated at room temperature. The diffractogram confirmed the presence of Mg2SnO4 and SnO2 phases. Photoluminescence spectroscopy identified broad and intense emission bands assigned to the Cr3+ cation occupation in octahedral Mg2SnO4 sites and an orange band assigned to SnO2 emission. All spectra were analyzed and interpreted according to crystal field theory and Tanabe–Sugano theory for the d3 electronic configuration. The broad and intense emission band covering the visible/near-infrared region suggests that this system may be a promising material for use as an active medium in a broadband light source at room temperature.

scholarly journals Preliminary Study of Ge-DLC Nanocomposite Biomaterials Prepared by Laser Codeposition

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 451 ◽  
Author(s):  
Miroslav Jelinek ◽  
Tomáš Kocourek ◽  
Karel Jurek ◽  
Michal Jelinek ◽  
Barbora Smolková ◽  
...  
Keyword(s):  
Room Temperature ◽  
Near Infrared ◽  
Biological Properties ◽  
Fused Silica ◽  
Film Properties ◽  
X Ray ◽  
Preliminary Study ◽  
Cytotoxicity Effects ◽  
Sem Morphology ◽  
Ge Doping

This paper deals with the synthesis and study of the properties of germanium-doped diamond-like carbon (DLC) films. For deposition of doped DLC films, hybrid laser technology was used. Using two deposition lasers, it was possible to arrange the dopant concentrations by varying the laser repetition rate. Doped films of Ge concentrations from 0 at.% to 12 at.% were prepared on Si (100) and fused silica (FS) substrates at room temperature. Film properties, such as growth rate, roughness, scanning electron microscopy (SEM) morphology, wavelength dependent X-ray spectroscopy (WDS) composition, VIS-near infrared (IR) transmittance, and biological properties (cytotoxicity, effects on cellular morphology, and ability to produce reactive oxygen species (ROS)) were studied in relation to codeposition conditions and dopant concentrations. The analysis showed that Ge-DLC films exhibit cytotoxicity for higher Ge doping.

scholarly journals Temperature-dependent optical constants of monolayer $${\text {MoS}}_2$$, $${\text {MoSe}}_2$$, $${\text {WS}}_2$$, and $${\text {WSe}}_2$$: spectroscopic ellipsometry and first-principles calculations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hsiang-Lin Liu ◽  
Teng Yang ◽  
Jyun-Han Chen ◽  
Hsiao-Wen Chen ◽  
Huaihong Guo ◽  
...  
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Room Temperature ◽  
Optical Constants ◽  
Near Infrared ◽  
Optical Band Gap ◽  
Transition Metal Dichalcogenides ◽  
First Principles Calculations ◽  
Temperature Dependent ◽  
Metal Dichalcogenides

Abstract The temperature-dependent ($$T = 4.5 \, \hbox {-} \, 500 \, \hbox {K}$$ T = 4.5 - 500 K ) optical constants of monolayer $${\text {MoS}}_2$$ MoS 2 , $${\text {MoSe}}_2$$ MoSe 2 , $${\text {WS}}_2$$ WS 2 , and $${\text {WSe}}_2$$ WSe 2 were investigated through spectroscopic ellipsometry over the spectral range of 0.73–6.42 eV. At room temperature, the spectra of refractive index exhibited several anomalous dispersion features below 800 nm and approached a constant value of 3.5–4.0 in the near-infrared frequency range. With a decrease in temperature, the refractive indices decreased monotonically in the near-infrared region due to the temperature-dependent optical band gap. The thermo-optic coefficients at room temperature had values from $$6.1 \times 10^{-5}$$ 6.1 × 10 - 5 to $$2.6 \times 10^{-4} \, \hbox {K}^{-1}$$ 2.6 × 10 - 4 K - 1 for monolayer transition metal dichalcogenides at a wavelength of 1200 nm below the optical band gap. The optical band gap increased with a decrease in temperature due to the suppression of electron–phonon interactions. On the basis of first-principles calculations, the observed optical excitations at 4.5 K were appropriately assigned. These results provide basic information for the technological development of monolayer transition metal dichalcogenides-based photonic devices at various temperatures.

Sign in / Sign up

Export Citation Format

Share Document