Characterizations of Zinc Oxynitride Powders Prepared Under Ammonia Gas Flow

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1523-1526 ◽  
Author(s):  
Takashi Sakamoto ◽  
Ryoji Saki ◽  
Toshihiro Moriga ◽  
Kei Ichiro Murai ◽  
Ichiro Nakabayashi
Keyword(s):  
Band Gap ◽  
Oxygen Content ◽  
Lattice Constant ◽  
Gas Flow ◽  
Optical Band Gap ◽  
Zinc Powder ◽  
Ammonia Gas

The anti-bixbyite-type zinc oxynitrides Zn 3( N1-xOx ) 2-y could be prepared by directly nitriding zinc powder under ammonia gas flow. Oxygen content x and amount of anion deficiency y decreased with increasing nitriding period at [Formula: see text]. Zn 3( N0.91O0.09 )1.98 could be obtained after the 168 hours of nitridation at [Formula: see text]. Reduction of both x and y, especially x, enhanced the lattice constant and reduced optical band gap of the oxynitride.

Effect of Various CF4/CH4 Flow Ratios on Structure and Optical Band Gap of Fluorinated Diamond-Like Carbon Thin Films

2010 ◽  
Vol 663-665 ◽  
pp. 312-315
Author(s):  
Jian Rong Xiao ◽  
Tao Tong ◽  
Yan Wei Li ◽  
Xin Hai Li
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Vapor Deposition ◽  
Gas Flow ◽  
Optical Band Gap ◽  
Chemical Vapor ◽  
Uniform Structure ◽  
Diamond Like Carbon ◽  
Radio Frequency Plasma ◽  
Frequency Plasma

Fluorinated diamond-like carbon (F-DLC) thin films are deposited using radio frequency plasma enhanced chemical vapor deposition under various gas flow ratios. The surface morphology of the F-DLC thin films deposited at lower gas flow ratios is a compact and uniform structure, and it became rough with the increase of gas flow ratios. The relative atomic contents of fluorine and chemical bonding configurations of C-Fx (x=1, 2, 3) in the thin films increases with the increase of gas flow ratios. The optical band gap of the thin films presents a decrease of different degree with the increase of gas flow ratios.

scholarly journals AB-INITIO CALCULATIONS OF THE OPTICAL BAND GAP OF TiO2 THIN FILMS

2004 ◽  
Vol 03 (04n05) ◽  
pp. 439-445 ◽  
Author(s):  
WILFRIED WUNDERLICH ◽  
LEI MIAO ◽  
MASAKI TANEMURA ◽  
SAKAE TANEMURA ◽  
PING JIN ◽  
...  
Keyword(s):  
Thin Films ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Band Gap ◽  
Lattice Constant ◽  
Optical Band Gap ◽  
Linear Increase ◽  
Tio2 Thin Films ◽  
Photocatalytic Application ◽  
Experimental Values

Titanium dioxide has been extensively studied in recent decades for its important photocatalytic application in environmental purification. The search for a method to narrow the optical band gap of TiO 2 plays a key role for enhancing its photocatalytic application. The optical band gap of epitaxial rutile and anatase TiO 2 thin films deposited by helicon magnetron sputtering on sapphire and on SrTiO 3 substrates was correlated to the lattice constants. The optical band gap of 3.03 eV for bulk-rutile increased for the thin films to 3.37 on sapphire. The band gap of 3.20 eV for bulk-anatase increases to 3.51 on SrTiO 3. In order to interpret this expansion, ab-initio calculations were performed using the Vienna ab-initio software. The calculations for rutile as well anatase show an almost linear increase of the band gap width with decreasing volume or increasing lattice constant a. The calculated band gap fits well with the experimental values. The conclusion from these calculations is, in order to achieve a smaller band gap for both, rutile or anatase, the lattice constant c has to be compressed, and a has to be expanded.

Influence of Metal Impurity Defects on the Electrical and Optical Properties of ITO Films on the PEN Substrates

2007 ◽  
Vol 1012 ◽  
Author(s):  
Hauk Han ◽  
Terry L Alford
Keyword(s):  
Optical Properties ◽  
Electrical Properties ◽  
Band Gap ◽  
Carrier Concentration ◽  
Oxygen Content ◽  
Optical Band Gap ◽  
Metal Impurity ◽  
Electrical And Optical Properties ◽  
Impurity States ◽  
Impurity Defects

AbstractIndium tin oxide (ITO) has drawn a great deal of attention due to its potential use as transparent electrodes in organic light emitting diode (OLED) and photovoltaic applications. This work focuses on understanding the role of impurity defects on the electrical conduction and transmittance of ITO. Thin films of ITO with high carrier concentration have been deposited onto polyethylene napthalate (PEN) substrates by electron-beam deposition without introduction of oxygen into the chamber. The influence of air anneals on the electrical and optical properties of ITO/PEN samples can is evaluated in terms of the oxygen content and is explained in terms of changes in the free electron concentrations. Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy analysis were used to determine the oxygen content in the film. A Hall effect measurement is used to determine the dependence of electrical properties on oxygen content. The electrical properties of the ITO films such as carrier concentration, electrical mobility, and resistivity abruptly changes after annealing in the air atmospheres. In addition, optical transmittance is improved from 7 to 71 % and optical band gap changes from 3.18 to 3.25 eV after heat treatment. The optical band gap narrowing behavior is because of impurity band and heavy carrier concentration. Metal impurity clusters form in the films as a result of oxygen deficiency and also generate defects and/or impurity states in the band gap and produces an optical band gap shift by merging of these impurity states and conduction band.

Influence of Oxygen to Argon Ratio on the Optical Band Gap of Bi3.25La0.75Fe1Ti2O12 Thin Films Deposited by RF Sputtering

2015 ◽  
Vol 15 (10) ◽  
pp. 8228-8232
Author(s):  
Jun Young Han ◽  
Chung Wung Bark
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Oxygen Content ◽  
Optical Band Gap ◽  
Rf Sputtering ◽  
Wide Band ◽  
Perovskite Oxides ◽  
Wide Band Gap ◽  
Visible Absorption ◽  
Simple Method

Achieving wide band gap tunability in ferroelectric perovskite oxides is desirable for the development of photovoltaic device applications and solar cells. To tune the wide band gap of perovskite oxides, ferroelectric iron doped BLT thin films (BLFT) on SrTiO3 substrates were fabricated by RF sputtering with simple control of the oxygen content. The structural and optical properties were analyzed by X-ray diffraction, scanning electron microscopy and ultraviolet-visible absorption spectroscopy. As the oxygen content in the mixed Ar+O2 atmosphere was increased from 0% to 50%, the optical band gap of the thin films were decreased from 2.8 eV to 2.64 eV. The BLFT film deposited at an Ar/O2 ratio of 1/1 exhibited a significantly lower optical band gap than the other samples. This simple sputtering approach to controlling the band gap with a simple method can provide a new candidate tool for manipulating optoelectronics devices.

Stability Investigation in the Optical Properties of Thermally Evaporated Ge5Se95-x Znx Thin Films

2015 ◽  
Vol 7 (3) ◽  
pp. 1923-1930
Author(s):  
Austine Amukayia Mulama ◽  
Julius Mwakondo Mwabora ◽  
Andrew Odhiambo Oduor ◽  
Cosmas Mulwa Muiva ◽  
Boniface Muthoka ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Optical Band Gap ◽  
Thermal Evaporation ◽  
Optical Transition ◽  
Bulk Material ◽  
Band Gap Energy ◽  
Optical Absorbance ◽  
Gap Energy ◽  
Constituent Elements

 Selenium-based chalcogenides are useful in telecommunication devices like infrared optics and threshold switching devices. The investigated system of Ge5Se95-xZnx (0.0 ≤ x ≤ 4 at.%) has been prepared from high purity constituent elements. Thin films from the bulk material were deposited by vacuum thermal evaporation. Optical absorbance measurements have been performed on the as-deposited thin films using transmission spectra. The allowed optical transition was found to be indirect and the corresponding band gap energy determined. The variation of optical band gap energy with the average coordination number has also been investigated based on the chemical bonding between the constituents and the rigidity behaviour of the system’s network.

scholarly journals Polymer Thermal Treatment Production of Cerium Doped Willemite Nanoparticles: An Analysis of Structure, Energy Band Gap and Luminescence Properties

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1118
Author(s):  
Ibrahim Mustapha Alibe ◽  
Khamirul Amin Matori ◽  
Mohd Hafiz Mohd Zaid ◽  
Salisu Nasir ◽  
Ali Mustapha Alibe ◽  
...  
Keyword(s):  
Solid State ◽  
Thermal Treatment ◽  
Band Gap ◽  
Optical Band Gap ◽  
Dopant Concentration ◽  
Blue Emission ◽  
Green Emission ◽  
Band Gap Energy ◽  
Solid State Lighting ◽  
Gap Energy

The contemporary market needs for enhanced solid–state lighting devices has led to an increased demand for the production of willemite based phosphors using low-cost techniques. In this study, Ce3+ doped willemite nanoparticles were fabricated using polymer thermal treatment method. The special effects of the calcination temperatures and the dopant concentration on the structural and optical properties of the material were thoroughly studied. The XRD analysis of the samples treated at 900 °C revealed the development and or materialization of the willemite phase. The increase in the dopant concentration causes an expansion of the lattice owing to the replacement of larger Ce3+ ions for smaller Zn2+ ions. Based on the FESEM and TEM micrographs, the nanoparticles size increases with the increase in the cerium ions. The mean particles sizes were estimated to be 23.61 nm at 1 mol% to 34.02 nm at 5 mol% of the cerium dopant. The optical band gap energy of the doped samples formed at 900 °C decreased precisely by 0.21 eV (i.e., 5.21 to 5.00 eV). The PL analysis of the doped samples exhibits a strong emission at 400 nm which is ascribed to the transition of an electron from localized Ce2f state to the valence band of O2p. The energy level of the Ce3+ ions affects the willemite crystal lattice, thus causing a decrease in the intensity of the green emission at 530 nm and the blue emission at 485 nm. The wide optical band gap energy of the willemite produced is expected to pave the way for exciting innovations in solid–state lighting applications.

scholarly journals Resonance and antiresonance in Raman scattering in GaSe and InSe crystals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Osiekowicz ◽  
D. Staszczuk ◽  
K. Olkowska-Pucko ◽  
Ł. Kipczak ◽  
M. Grzeszczyk ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Temperature Effect ◽  
Band Gap ◽  
Raman Spectra ◽  
Quantum Interference ◽  
Optical Band Gap ◽  
Phonon Coupling ◽  
Phonon Modes ◽  
Electron Phonon Coupling ◽  
Resonant Raman

AbstractThe temperature effect on the Raman scattering efficiency is investigated in $$\varepsilon$$ ε -GaSe and $$\gamma$$ γ -InSe crystals. We found that varying the temperature over a broad range from 5 to 350 K permits to achieve both the resonant conditions and the antiresonance behaviour in Raman scattering of the studied materials. The resonant conditions of Raman scattering are observed at about 270 K under the 1.96 eV excitation for GaSe due to the energy proximity of the optical band gap. In the case of InSe, the resonant Raman spectra are apparent at about 50 and 270 K under correspondingly the 2.41 eV and 2.54 eV excitations as a result of the energy proximity of the so-called B transition. Interestingly, the observed resonances for both materials are followed by an antiresonance behaviour noticeable at higher temperatures than the detected resonances. The significant variations of phonon-modes intensities can be explained in terms of electron-phonon coupling and quantum interference of contributions from different points of the Brillouin zone.

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