scholarly journals Pressure-Tuneable Visible-Range Band Gap in the Ionic Spinel Tin Nitride

2018 ◽  
Vol 130 (36) ◽  
pp. 11797-11802 ◽  
Author(s):  
John S. C. Kearney ◽  
Miglė Graužinytė ◽  
Dean Smith ◽  
Daniel Sneed ◽  
Christian Childs ◽  
...  
Keyword(s):  
Band Gap ◽  
Visible Range ◽  
Tin Nitride

scholarly journals Pressure‐Tuneable Visible‐Range Band Gap in the Ionic Spinel Tin Nitride

2018 ◽  
Vol 57 (36) ◽  
pp. 11623-11628 ◽  
Author(s):  
John S. C. Kearney ◽  
Miglė Graužinytė ◽  
Dean Smith ◽  
Daniel Sneed ◽  
Christian Childs ◽  
...  
Keyword(s):  
Band Gap ◽  
Visible Range ◽  
Tin Nitride

Spectroscopic Analysis and Synthesis of Wide Band Gap CdS Quantum Dots Using Colloidal Synthesis Technique at Low Temperature

2009 ◽  
Vol 67 ◽  
pp. 191-196 ◽  
Author(s):  
Lubna Hashmi ◽  
M.S. Qureshi ◽  
R.N. Dubey ◽  
M.M. Malik ◽  
Ishrat Alim ◽  
...  
Keyword(s):  
Low Temperature ◽  
Band Gap ◽  
Spectroscopic Analysis ◽  
Quantum Confinement Effect ◽  
Wide Band ◽  
Colloidal Synthesis ◽  
Visible Range ◽  
Wide Band Gap ◽  
Synthesis Technique ◽  
Analysis And Synthesis

A broad range of II-VI materials has been investigated in order to produce light in the full visible range for optoelectronic applications. The present investigation was carried out for the spectroscopic analysis and synthesis of wide band gap cadmium sulfide nanoparticles. Large-band gap semiconductors have the added advantage in that; they can support higher electric field before breaking down, which means that they can be used for high-power electronic devices.Synthesis has been carried out using colloidal synthesis technique at low temperature. The size, stabilization and optical properties were studied using UV-vis Spectrophotometer and Spectroflourometer. Further, the structural studies of synthesized powder were carried out using X-ray diffraction technique; which also confirms the formation of desired product. The capping ligand and the impurities present in the sample were characterized by Fourier transform infra red spectroscopy. Synthesized CdS powder dispersed in aqueous media gave the value of 193 nm for the onset wavelength using UV-vis spectrophotometer, which is significantly blue-shifted compared to bulk CdS and shows the quantum confinement effect. From the onset wavelength the radius of CdS quantum dot calculated using the Brus equation was found to be ca. 0.7 nm.

scholarly journals Study of Band Gap of Silver Nanoparticles—Titanium Dioxide Nanocomposites

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
P. Barone ◽  
F. Stranges ◽  
M. Barberio ◽  
D. Renzelli ◽  
A. Bonanno ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Band Gap ◽  
Chemical Properties ◽  
Photoelectrochemical Cells ◽  
Visible Range ◽  
X Ray ◽  
Optical Absorbance ◽  
Laser Ablation Process ◽  
Uv Visible ◽  
And Chemical Properties

The optical and chemical properties of Ag/TiO2nanocomposites were investigated to explore the possibilities of incorporating these new materials in Gratzel photoelectrochemical cells. The nanocomposites were obtained doping TiO2, in both allotropic species anatase and rutile, with silver nanoparticles (grown by laser ablation process). X-ray photoelectron data indicate the absence of Ag-Ti chemical bonds, while measurements of photoluminescence and optical absorbance in UV-visible range show a quench in photoluminescence emission of about 50% and an increase in visible absorbance of about 20%. Measurements of optical band gap, obtained by Tauc’s equation, indicate a variation of about 1.6 eV.

Novel Materials Based on Organic-Tungsten Oxide Hybrid Systems

2003 ◽  
Vol 775 ◽  
Author(s):  
Bridget Ingham ◽  
Shen V. Chong ◽  
Jeff L. Tallon
Keyword(s):  
Band Gap ◽  
Tungsten Oxide ◽  
Hybrid Materials ◽  
Absorption Edge ◽  
Interlayer Spacing ◽  
Visible Range ◽  
Spectroscopic Techniques ◽  
Length Changes ◽  
Indirect Band Gap ◽  
Experimental Values

AbstractThe physical and electronic properties of tungsten oxide and some related hybrid materials have been examined via various spectroscopic techniques and the results complemented by ab initio computation. Hybrid materials based on intercalated straight-chain σ,ω-diaminoalkanes in between sheets of corner-shared tungsten-oxide octahedra exhibit from XRD a linear expansion in the interlayer spacing with increasing number of carbon atoms in the amines. UV-visible diffuse reflectance spectra of several hybrid powders indicate a dominant absorption edge centred at 4.0 eV, with no apparent trend among the different samples as the alkyl chain length changes. This is higher than that of tungsten trioxide powder, which has an absorption edge centred at 2.8 eV. Ab initio calculations show that these experimental values may relate to the indirect band-gap energies of the respective compounds rather than the optical band gap. This was confirmed from the absorption coefficient results of WO3 thin films which yield a strong edge at 4.0 eV. Similar measurements of hybrid films with 1,12-diaminododecane as the organic spacer showed absorption throughout the visible range, with weak features at 4.2 and 4.9 eV.

Photonic band gap in the visible range in a three-dimensional solid state lattice

1996 ◽  
Vol 63 (6) ◽  
pp. 613-616 ◽  
Author(s):  
V. N. Bogomolov ◽  
S. V. Gaponenko ◽  
A. M. Kapitonov ◽  
A. V. Prokofiev ◽  
A. N. Ponyavina ◽  
...  
Keyword(s):  
Solid State ◽  
Band Gap ◽  
Photonic Band Gap ◽  
Three Dimensional ◽  
Visible Range ◽  
Photonic Band

scholarly journals Optical Properties of Undoped and Indium-doped Tin Oxide Thin Films

2011 ◽  
Vol 35 (1) ◽  
pp. 99-111 ◽  
Author(s):  
Fatema Rezwana Chowdhury ◽  
Shamima Choudhury ◽  
Firoz Hasan ◽  
Tahmina Begum
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Tin Oxide ◽  
Optical Transmittance ◽  
Band Gap Energy ◽  
Visible Range ◽  
Absorption Region ◽  
Gap Energy ◽  
Glass Substrates ◽  
In Doping

Thin films of Tin Oxide (SnO2), having thickness of 200 nm, were formed on to glass substrates by thermal evaporation of high-purity SnO2 powder in vacuum at various substrate temperatures (TS), ranging between 25 and 200°C. SnO2 films with varying thickness were also prepared for a fixed TS = 100°C. Further, doping of SnO2 films with Indium (In) was accomplished through solid state diffusion process by successive deposition of SnO2 and In films and subsequent annealing at 200°C for 10 minutes. Both undoped and doped films were characterized optically by UV-VIS-NIR spectrophotometry in the photon wavelength ranging from 300 to 2500 nm. In the visible photon wavelength range, the average optical transmittance (T%) of the films with varying TS was found to be 85%. The maximum value of T % was found to be 89 % around the wavelength of 700nm. The variation of absorption coefficient with photon energy in the fundamental absorption region is the steepest for TS = 100°C. The sub-band gap (SBG) absorption is also minimum for this Ts. A fluctuating behavior of the band gap energy (Eg) with Ts is observed attaining the highest value of 3.59 eV for Ts = 100°C. The band gap energy increases with thickness but T% in the visible range decreases. The T% in the visible range varies inversely with indium doping, being highest for undoped films. The Eg increases upto 2 wt% In doping and gradually decreases for enhanced doping. It seems reasonable to conclude that In doping does not bring favorable optical characteristics. Undoped SnO2 films having thickness of 200 nm and formed at substrate temperature of 100°C yield essential acceptable properties for photovoltaic applications.DOI: http://dx.doi.org/10.3329/jbas.v35i1.7975Journal of Bangladesh Academy of Sciences, Vol.35, No.1, 99-111, 2011

Properties of Nanostructure Formed on SiO2/Si Interface by Laser Radiation

2007 ◽  
Vol 131-133 ◽  
pp. 559-562 ◽  
Author(s):  
Arthur Medvid ◽  
Igor Dmitruk ◽  
Pavels Onufrijevs ◽  
Iryna Pundyk
Keyword(s):  
Optical Properties ◽  
Laser Radiation ◽  
Band Gap ◽  
Quantum Confinement ◽  
Quantum Confinement Effect ◽  
Confinement Effect ◽  
Visible Range ◽  
Pulsed Nd:Yag Laser ◽  
Self Organized ◽  
Graded Band Gap

The aim of this work is to study optical properties of Si nanohills formed on the SiO2/Si interface by the pulsed Nd:YAG laser radiation. Nanohills which are self-organized on the surface of Si, are characterized by strong photoluminescence in the visible range of spectra with long wing in the red part of spectra. This peculiarity is explained by Quantum confinement effect in nanohillsnanowires with graded diameter. We have found a new method for graded band gap semiconductor formation using an elementary semiconductor. Graded change of band gap arises due to Quantum confinement effect.

Effect of Atmosphere Temperature on Physical Properties of ZnO/Ag/ZnO on PET Films

2014 ◽  
Vol 988 ◽  
pp. 125-129 ◽  
Author(s):  
Yun Hae Kim ◽  
Jin Woo Lee ◽  
Riichi Murakami ◽  
Dong Myung Lee ◽  
Jin Cheol Ha ◽  
...  
Keyword(s):  
Band Gap ◽  
Sheet Resistance ◽  
Chemical Properties ◽  
Raw Material ◽  
Silver Layer ◽  
Visible Range ◽  
Potential Candidate ◽  
Practical Applications ◽  
Ito Film ◽  
Transparent Conducting

Transparent conductive layers on flexible substrates are important components of today’s optoelectronic technology. They are used in filters for plasma displays, low-e windows, solar cells, etc. At present, in-doped indium oxide (ITO) layers on PET substrate is the predominant transparent conducting oxide film in diverse practical applications. However, ITO is a relatively expensive material because indium is not abundant, but aluminum-doped zinc oxide (AZO) film is emerging as an alternative potential candidate to ITO thin film due to its abundance as a raw material, nontoxic nature, cost-effectiveness, easy fabrication, and good stability in plasma. They have, however, several drawbacks: they exhibit relatively high electrical resistance (sheet resistance, 20-200Ω), considerable emissivity, and significant absorption in the spectral region 1-2μm, in which transition from high transmittance to high reflectance takes place. Furthermore, these films do not block solar thermal radiation (0.7-3μm), which may cause overheating problems to devices such as electro-chromic and photovoltaic devices. On the other hand, ITO/Ag/ITO multilayer films are used to achieve high transparent conducting properties. A thin silver layer of about 10nm thickness is embedded between two ITO layers. The ITO/Ag/ITO film has very low sheet resistance, high optical transparency in the visible range, relatively lower thickness than single-layered ITO film, and better durability than single-layered silver film. In terms of ZnO, which is a wide direct band-gap semiconductor, ZnO has a band-gap energy of 3.37 eV with a binding energy as high as 60 meV at room temperature. ZnO has been applied to various domains for excellent physical and chemical properties, such as piezoelectric sensors, rheostats , gas sensors, semiconductor lasers, and transparent conductive films.

Nitrogen – Doped SnO2 Thin Films Prepared by Direct Current Magnetron Sputtering

2013 ◽  
Vol 770 ◽  
pp. 169-172 ◽  
Author(s):  
Prayoon Suapadkorn ◽  
Worawarong Rakreungdet ◽  
Tula Jutarosaga ◽  
Wattana Samanjit
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Band Gap ◽  
Flow Rate ◽  
Hole Concentration ◽  
Visible Range ◽  
Intrinsic Defect ◽  
Average Crystalline Size ◽  
Working Pressure ◽  
Nitrogen Doped

Nitrogen - doped tin oxide (N-doped SnO2) thin films were prepared on unheated glass substrate by dc magnetron sputtering of a Sn target in gas mixtures of O2 and N2. The N2 flow rates were varied from 0 to 15 SCCM with the same working pressure of 1×10-2 Torr. The as-deposited films were annealed in vacuum at 400 °C for 1 h. The films structure, electrical properties and optical properties were characterized by X-ray diffraction (XRD), 4-point probe and Hall effect measurement and portable fiber optic UV-vis spectrometer, respectively. The observed XRD patterns of films showed preferred (101) orientation of the SnO2 tetragonal structure. The average crystalline size of the (101) diffraction peak decreased from 5.10 to 4.07 nm with N2 flow rate increased. Hall measurement indicated that resistivity increased and carrier concentrations decreased as N2 flow rate increased. The carrier concentrations decreased because N atoms substituted oxygen atom in SnO2 lattice. The N atoms may forms acceptor level in SnO2 band gap resulting in hole generation. The electron concentration from intrinsic defect were neutralized with the hole concentration. The carrier concentration decreased from 3.42×1017 cm-3 for un-doped SnO2 to the order of 1014 cm-3. The average percent transmittance of un-doped SnO2 of about 77.5% in visible range (400-700 nm) decreased to 60% with increasing N2 flow rate. The optical band gap decreased from 3.64 eV for un-doped SnO2 to 3.45 eV for N-doped SnO2 films.

Preparation and Wide Tunable Band-Gap Energies of PbTe Nanocrystals Using Glycerin as a Capping Ligand

2014 ◽  
Vol 904 ◽  
pp. 81-85
Author(s):  
Xing Li Ren ◽  
Xing Rong Jiang
Keyword(s):  
Band Gap ◽  
Blue Shift ◽  
Visible Range ◽  
X Ray Diffraction ◽  
Size Dependent ◽  
Near Ir ◽  
Transmission Electron ◽  
Novel Method ◽  
Uv Visible ◽  
Tunable Band Gap

PbTe nanocrystals (NCs) have been synthesized by a novel method at low temperature. Pb acetate being solved in glycerol and Te in TOP solution were used as the precursors for the preparation of PbTe nanocrystals. The as-prepared products were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), UVvis absorption, Fourier transform infrared spectroscopy (FTIR). These data, together with analysis of the absorption spectra, allowed us to observe the size dependence of the peaks in the absorption spectrum. The size-dependent optical spectra of the PbTe nanocrystals exhibits wide tunable band gap energies varying from UV visible range to near IR region, which corresponds to a huge blue shift of 3.0 eV in comparison to the bulk counterpart. Keywords: 1. PbTe nanocrystals, 2. optical properties, 3. wide tunable band gap, 4. microstructure

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