scholarly journals The Effect of Band-Gap on TiO2 Thin Film Considering Various Parameters

2021 ◽  
Vol 19 ◽  
pp. 45-52
Author(s):  
Majedul Haque Mithun ◽  
Abu Sayed ◽  
Imteaz Rahaman
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Tio2 Thin Film ◽  
Sol Gel ◽  
Band Gaps ◽  
Tio2 Thin Films ◽  
Direct Band Gap ◽  
Direct Band ◽  
Indirect Band Gap ◽  
Absorbance Spectra

The aim of this work is to measure the effect of band-gap on TiO2 thin films by changing tetrabutylorthotitanate (TBOT), diethanolamine (DEA), and temperature. The sol-gel method is experimentally introduced to find out the better band-gap of TiO2 thin films by varying the concentration of TBOT (4 ml to 10 ml), DEA (2 ml to 5 ml), and temperature (350°C to 650°C). With the help of an ultraviolet-visible spectrophotometer for the wavelength of 300-900 nm, these thin films are characterized concerning optical properties (transmittance spectra, absorbance spectra, direct band-gap, and indirect band-gap). The direct and indirect band-gaps are found 3.38 eV and 3.25 eV respectively, which are close to or within the standard band-gap range of TiO2 (3.2 eV to 3.35 eV) and are found at 8 ml TBOT, 3 ml DEA, and a temperature of 550°C.

scholarly journals Low-temperature photoluminescence of CuSe2 nano-objects in selenium thin films

2017 ◽  
Vol 11 (2) ◽  
pp. 127-135 ◽  
Author(s):  
Martina Gilic ◽  
Milica Petrovic ◽  
Jovana Cirkovic ◽  
Novica Paunovic ◽  
Svetlana Savic-Sevic ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Room Temperature ◽  
Band Gaps ◽  
Photoluminescence Spectra ◽  
Indirect Transition ◽  
Direct Transition ◽  
Direct Band Gap ◽  
Vis Spectroscopy ◽  
Direct Band

Thin films of CuSe2 nanoparticles embedded in selenium matrix were prepared by vacuum evaporation method on a glass substrate at room temperature. The optical properties of the films were investigated by photoluminescence spectroscopy (T=20-300K) and UV-VIS spectroscopy (T = 300K). Surface morphology was investigated by scanning electron microscopy. The band gap for direct transition in CuSe2 was found to be in the range of 2.72-2.75 eV and that for indirect transition is in the range of 1.71-1.75 eV determined by UV-VIS spectroscopy. On the other hand, selenium exhibits direct band gap in the range of 2.33-2.36 eV. All estimated band gaps slightly decrease with the increase of the film thickness. Photoluminescence spectra of the thin films clearly show emission bands at about 1.63 and 2.32 eV at room temperature, with no shift observed with decreasing temperature. A model was proposed for explaining such anomaly.

Optical Studies of Poly (N-Carbazole) (PVK) Blending with Polyvinylpyrrolidone (PVP) Using Tauc/Davis-Mott Model

2013 ◽  
Vol 652-654 ◽  
pp. 527-531 ◽  
Author(s):  
A.N. Alias ◽  
T.I. Tunku Kudin ◽  
Z.M. Zabidi ◽  
M.K. Harun ◽  
Ab Malik Marwan Ali ◽  
...  
Keyword(s):  
Band Gap ◽  
Urbach Energy ◽  
Quartz Substrate ◽  
Optical Studies ◽  
Direct Band Gap ◽  
Mott Model ◽  
Blended Polymer ◽  
Electronic Parameters ◽  
Direct Band ◽  
Indirect Band Gap

The optical absorption spectra of blended poly (N-carbazole) (PVK) with polyvinylpyrrolidone (PVP) in various compositions are investigated. A doctor blade technique was used to coat the blended polymer on a quartz substrate. The electronic parameters such as absorption edge (Ee), allowed direct band gap (Ed), allowed indirect band gap (Ei), Urbach edge (Eu) and steepness parameter (γ) were calculated using Tauc/Davis-Mott Model. The results reveal that the Ee, Ed and Ei increase with increasing of PVP ratio. There also have variation changing in Urbach energy and steepness parameter.

scholarly journals Microstructure Evolution of Ag/TiO2 Thin Film

2021 ◽  
Vol 7 (1) ◽  
pp. 14
Author(s):  
Dewi Suriyani Che Halin ◽  
Kamrosni Abdul Razak ◽  
Mohd Arif Anuar Mohd Salleh ◽  
Mohd Izrul Izwan Ramli ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Growth Rate ◽  
Synchrotron Radiation ◽  
Tio2 Thin Film ◽  
Sol Gel ◽  
Tio2 Thin Films ◽  
Contact Mode ◽  
X Ray ◽  
Radiation Imaging

Ag/TiO2 thin films were prepared using the sol-gel spin coating method. The microstructural growth behaviors of the prepared Ag/TiO2 thin films were elucidated using real-time synchrotron radiation imaging, its structure was determined using grazing incidence X-ray diffraction (GIXRD), its morphology was imaged using the field emission scanning electron microscopy (FESEM), and its surface topography was examined using the atomic force microscope (AFM) in contact mode. The cubical shape was detected and identified as Ag, while the anatase, TiO2 thin film resembled a porous ring-like structure. It was found that each ring that coalesced and formed channels occurred at a low annealing temperature of 280 °C. The energy dispersive X-ray (EDX) result revealed a small amount of Ag presence in the Ag/TiO2 thin films. From the in-situ synchrotron radiation imaging, it was observed that as the annealing time increased, the growth of Ag/TiO2 also increased in terms of area and the number of junctions. The growth rate of Ag/TiO2 at 600 s was 47.26 µm2/s, and after 1200 s it decreased to 11.50 µm2/s and 11.55 µm2/s at 1800 s. Prolonged annealing will further decrease the growth rate to 5.94 µm2/s, 4.12 µm2/s and 4.86 µm2/s at 2400 s, 3000 s and 3600 s, respectively.

Preparation and characterization of V2O5 doped SiO2-TiO2 thin films

2012 ◽  
Vol 2 (1) ◽  
Author(s):  
Marek Nocuń ◽  
Sławomir Kwaśny
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Dip Coating ◽  
Band Gap Energy ◽  
Tio2 Thin Films ◽  
Glass Substrates ◽  
Gel Technique

AbstractIn our investigation, V doped SiO2/TiO2 thin films were prepared on glass substrates by dip coating sol-gel technique. Chemical composition of the samples was studied by X-ray photoelectron spectroscopy (XPS). Transmittance of the samples was characterized using UV-VIS spectrophotometry. Subsequently band-gap energy (Eg) was estimated for these films. Powders obtained from sols were characterized by FTIR spectroscopy. It was found that vanadium decreases optical band gap of SSiO2/TiO2 films.

scholarly journals Biaxial strain modulated the electronic structure of hydrogenated 2D tetragonal silicene

RSC Advances ◽  
2019 ◽  
Vol 9 (72) ◽  
pp. 42245-42251
Author(s):  
Haoran Tu ◽  
Jing Zhang ◽  
Zexuan Guo ◽  
Chunyan Xu
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Biaxial Strain ◽  
Direct Band Gap ◽  
Direct Band ◽  
Indirect Band Gap

Hydrogenation can open the band gap of 2D tetragonal silicene, α-SiH is semiconductors with a direct band gap of 2.436 eV whereas β-SiH is indirect band gap of 2.286 eV. The band gap of α-SiH, β-SiH and γ-SiH can be modulated via biaxial strain.

Spray Chemical Vapor Deposition of CuInS2 Thin Films for Application in Solar Cell Devices

1997 ◽  
Vol 495 ◽  
Author(s):  
Jennifer A. Hollingsworth ◽  
William E. Buhro ◽  
Aloysius F. Hepp ◽  
Philip P. Jenkins ◽  
Mark A. Stan
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Band Gap ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Fused Silica ◽  
Direct Band Gap ◽  
Cuins2 Thin Films ◽  
Potential Applications ◽  
Direct Band

ABSTRACTChalcopyrite CuInS2 is a direct band gap semiconductor (1.5 eV) that has potential applications in photovoltaic thin film and photoelectrochemical devices. We have successfully employed spray chemical vapor deposition using the previously known, single-source, metalorganic precursor, (Ph3P)2CuIn(SEt)4, to deposit CuInS2 thin films. Stoichiometric, polycrystalline films were deposited onto fused silica over a range of temperatures (300–400 °C). Morphology was observed to vary with temperature: spheroidal features were obtained at lower temperatures and angular features at 400 °C. At even higher temperatures (500 °C), a Cu-deficient phase, CuIn5S8, was obtained as a single phase. The CuInS2 films were determined to have a direct band gap of ca. 1.4 eV.

LASER-INDUCED MULTIPHOTON PHOTOCONDUCTIVITY IN DIRECT AND INDIRECT BAND GAP CRYSTALS USING Z-SCAN TECHNIQUE

2009 ◽  
Vol 23 (23) ◽  
pp. 2783-2789 ◽  
Author(s):  
ARUN GAUR ◽  
D. K. SHARMA ◽  
K. S. SINGH ◽  
NAGESHWAR SINGH
Keyword(s):  
Absorption Coefficient ◽  
Band Gap ◽  
Laser Pulses ◽  
Beam Waist ◽  
Photon Absorption ◽  
Nanosecond Laser ◽  
Direct Band Gap ◽  
Direct Band ◽  
Nanosecond Laser Pulses ◽  
Indirect Band Gap

Nanosecond laser pulses have employed the photoconductive Z-scan technique. Photoconductivity traces measured by moving the sample across the laser beam waist were used for measuring two and three-photon absorption processes. The value of the three-photon absorption coefficient β3=9.6×10-10 cm 3/ GW 2 in the case of direct, and 8.96×10-12 cm 3/ GW 2 and 5.0×10-12 cm 3/ GW 2 in the case of indirect band gap crystals have been estimated from a comparison of traces measured by exciting the sample with the first and second harmonics of Nd : YAG laser. The low value of β3 in the case of indirect band gap crystals compared to direct band gap crystals is attributed to phonon-assisted transitions.

SHIFT OF BAND GAP FROM DIRECT TO INDIRECT AND OPTICAL RESPONSE OF LiF UNDER PRESSURE

2013 ◽  
Vol 27 (09) ◽  
pp. 1350061 ◽  
Author(s):  
A. SAJID ◽  
G. MURTAZA ◽  
A. H. RESHAK
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Lithium Fluoride ◽  
Pressure Range ◽  
Pressure Effect ◽  
Indirect Transition ◽  
Direct Band Gap ◽  
Direct Band ◽  
Indirect Band Gap

We hereby are reporting the transition pressure at which lithium fluoride ( LiF ) compound transforms from direct band gap to indirect band gap insulator on the basis of FP-LAPW calculations. The fundamental band gap of LiF compound suffers direct to indirect transition at a pressure of 70 GPa. The study of the pressure effect on the optical properties e.g. dielectric function, reflectivity, refractive index and optical conductivity of LiF in the pressure between 0–100 GPa, shows that this pressure range is very critical for LiF compound as there are significant changes in the optical properties of this compound.

scholarly journals Nickel doping effect on the structural and optical properties of indium sulfide thin films by SILAR

2018 ◽  
Vol 16 (1) ◽  
pp. 757-762 ◽  
Author(s):  
Fatma Göde ◽  
Serdar Ünlü
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Band Gap ◽  
Doping Concentration ◽  
Indium Sulfide ◽  
Ni Doping ◽  
X Ray ◽  
Direct Band Gap ◽  
Direct Band ◽  
Ni Dopant

AbstractUndoped and nickel doped indium sulfide (In2S3:Ni) thin films have been deposited on indium tin oxide (ITO) coated glass substrates by successive ionic layer adsorption and reaction (SILAR) method. The doping concentration of Ni has been adjusted as 4%, 5% and 6% (in molar ratio of nickel ions to indium ions). The effects of Ni doping on the structural, morphological, compositional and optical properties of the In2S3 thin films are investigated. The x-ray diffraction patterns show that deposited film has cubic structure with amorphous nature of In2S3 and its crystallinity deteriorates with increasing doping concentration. The SEM measurements show that the surface morphology of the films is affected from the Ni incorporation. The direct band gap of the films decreases from 2.33 eV to 1.61 eV with increasing Ni dopant. Energy dispersive x-ray spectroscopy (EDS) has been used to evaluate the chemical composition and shown that S/(Ni+In) ratio in films decreases from 1.18 to 0.40 with Ni content. Optical properties of the films have been performed by a UV-Vis spectrophotometer. The direct band gap of the films decreases from 2.33 eV to 1.61 eV with increasing Ni dopant. Moreover, optical parameters of the films such as refractive index (𝑛), extinction coefficient (k), real (ε1) and imaginary (ε2) parts of dielectric constant have been determined by using absorbance and transmittance spectra. The investigations showed that the Ni doping has a significant effect on the physical properties of SILAR produced In2S3 thin films.

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