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.

scholarly journals Optical properties of CuSe thin films - band gap determination

2017 ◽  
Vol 49 (2) ◽  
pp. 167-174 ◽  
Author(s):  
Milica Petrovic ◽  
Martina Gilic ◽  
Jovana Cirkovic ◽  
Maja Romcevic ◽  
Nebojsa Romcevic ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Band Gap ◽  
Room Temperature ◽  
Nir Spectroscopy ◽  
Copper Selenide ◽  
Photoluminescence Spectra ◽  
Indirect Transition ◽  
Direct Transition ◽  
Scanning Electron

Copper selenide thin films of three different thicknesses have been prepared by vacuum evaporation method on a glass substrate at room temperature. The optical properties of the films were investigated by UV-VIS-NIR spectroscopy and photoluminescence spectroscopy. Surface morphology was investigated by field-emission scanning electron microscopy. Copper selenide exhibits both direct and indirect transitions. The band gap for direct transition is found to be ~2.7 eV and that for indirect transition it is ~1.70 eV. Photoluminescence spectra of copper selenide thin films have also been analyzed, which show emission peaks at 530, 550, and 760 nm. The latter corresponds to indirect transition in investigated material.

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.

Raman Scattering and Photoluminescence of Spontaneously Ordered Ga0.5In0.5P Alloy

1996 ◽  
Vol 452 ◽  
Author(s):  
G. H. Li ◽  
Z. X. Liu ◽  
H. X. Han ◽  
Z. P. Wang ◽  
J. R. Dong ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Band Gap ◽  
Room Temperature ◽  
Band Gaps ◽  
Photoluminescence Spectra ◽  
Zinc Blende ◽  
Gaas Substrates ◽  
Ordered Alloys ◽  
Direct Band ◽  
Zinc Blende Structure

AbstractSamples of the spontaneously ordered Ga0.5In0.5P alloys were grown by the MOCVD method on [001]-oriented GaAs substrates. The thickness of the epitaxal layer is about 2 μm. Raman scattering and photoluminescence spectra have been measured at room temperature. The result from photoluminescence measurement indicates that the direct-band gaps of the spontaneously ordered samples are lower than that of the disordered sample. Three scattering peaks have been observed in the Raman spectra, corresponding to the GaP-like LO, InP-like LO and InP-like TO modes in the alloys, respectively. The frequencies of the GaP- and InP-like LO modes increase with the decrease of the band-gap of the ordered alloys. It is related to the formation of the (GaP)1/(InP)1 monolayer superlattice along [111] direction in the ordered alloys. The polarization properties of the ordered alloys are similar to those of the bulk III-V semiconductors with the zinc-blende structure.

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.

scholarly journals Effects of the Argon Pressure on the Optical Band Gap of Zinc Oxide Thin Films Grown by Nonreactive RF Sputtering

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
M. Acosta ◽  
I. Riech ◽  
E. Martín-Tovar
Keyword(s):  
Thin Films ◽  
Zinc Oxide ◽  
Band Gap ◽  
Room Temperature ◽  
Optical Band Gap ◽  
Rf Sputtering ◽  
Argon Pressure ◽  
Band Gaps ◽  
Zno Thin Films ◽  
Optical Band Gaps

Zinc oxide (ZnO) thin films were grown by nonreactive RF sputtering at room temperature under varying argon pressures (PAr). Their optical band gap was found to increase from 3.58 to 4.34 eV when the argon pressure increases from 2.67 to 10.66 Pa. After annealing at 200°C and 500°C, optical band gaps decrease considerably. The observed widening of the band gap with increasingPArcan be understood as being a consequence of the poorer crystallinity of films grown at higher pressures. Measurements of morphological and electrical properties of these films correlate well with this picture. Our main aim is to understand the effects ofPAron several physical properties of the films, and most importantly on its optical band gap.

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.

Direct band gap light emission and detection at room temperature in bulk germanium diodes with HfGe/Ge/TiN structure

2016 ◽  
Vol 602 ◽  
pp. 43-47 ◽  
Author(s):  
Dong Wang ◽  
Takayuki Maekura ◽  
Keisuke Yamamoto ◽  
Hiroshi Nakashima
Keyword(s):  
Band Gap ◽  
Room Temperature ◽  
Light Emission ◽  
Direct Band Gap ◽  
Direct Band

Room-temperature direct band-gap electroluminescence from germanium (111)-fin light-emitting diodes

2017 ◽  
Vol 56 (3) ◽  
pp. 032102 ◽  
Author(s):  
Kazuki Tani ◽  
Shin-ichi Saito ◽  
Katsuya Oda ◽  
Makoto Miura ◽  
Yuki Wakayama ◽  
...  
Keyword(s):  
Band Gap ◽  
Room Temperature ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Direct Band Gap ◽  
Direct Band

scholarly journals Indium Sulfide and Ternary In-S-O Nanowires for Optoelectronic Applications

2012 ◽  
Vol 18 (S5) ◽  
pp. 121-122 ◽  
Author(s):  
J. Bartolomé ◽  
D. Maestre ◽  
A. Cremades ◽  
J. Piqueras
Keyword(s):  
Solar Cell ◽  
Band Gap ◽  
Material Properties ◽  
Room Temperature ◽  
High Efficiency ◽  
Processing Parameters ◽  
Indium Sulfide ◽  
Direct Band Gap ◽  
Direct Band ◽  
Optoelectronic Applications

Indium sulfide (In2S3) is a promising semiconductor material for window layers in solar cell devices and other optoelectronic applications as it presents a direct band gap around 2.0 eV at room temperature, and large photosensitivity and photoconductivity. The presence of several polymorphic structures depending on the processing parameters is also of interest to tailor the required material properties for different applications. It is currently being investigated for high efficiency solar cell based on CuInS2-In2S3 heterostructures, replacing CdS layers. Few studies have been reported on nanostructured In2S3 grown by several methods.

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