Temperature Dependence of the Band-Gap Energy and Sub-Band-Gap Absorption Tails in Strongly Quantized ZnSe Nanocrystals Deposited as Thin Films

2010 ◽  
Vol 114 (36) ◽  
pp. 15280-15291 ◽  
Author(s):  
Biljana Pejova ◽  
Bahattin Abay ◽  
Irina Bineva
Keyword(s):  
Thin Films ◽  
Temperature Dependence ◽  
Band Gap ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Znse Nanocrystals

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.

Fabrication and Photoelectrochemical Characterization of Fe, Co, Ni and Cu-Doped TiO2 Thin Films

2013 ◽  
Vol 764 ◽  
pp. 266-283 ◽  
Author(s):  
Ibram Ganesh ◽  
Rekha Dom ◽  
P.H. Borse ◽  
Ibram Annapoorna ◽  
G. Padmanabham ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Metal Ions ◽  
Band Gap ◽  
Metal Ion ◽  
Band Gap Energy ◽  
Chemical Compositions ◽  
Gap Energy ◽  
Glass Substrates ◽  
Photoelectrochemical Characterization

Different amounts of Fe, Co, Ni and Cu-doped TiO2 thin films were prepared on fluorine doped tin oxide (FTO) coated soda-lime glass substrates by following a conventional sol-gel dip-coating technique followed by heat treatment at 550 and 600°C for 30 min. These thin films were characterized for photo-current, chronoamperometry and band-gap energy values. The chemical compositions of metals-doped TiO2 thin films on FTO glass substrates were confirmed by XPS spectroscopic study. The metal-ions doped TiO2 thin films had a thickness of <200 nm="" optical="" transparency="" of="">80%, band-gap energy of >3.6 eV, and a direct band-to-band energy transition. The photoelectrochemical (PEC) studies revealed that all the metal-ions doped TiO2 thin films exhibit n-type semi-conducting behavior with a quite stable chronoamperometry and photo-currents that increase with the increase of applied voltage but decrease with the dopant metal-ion concentration in the thin film. Furthermore, these thin films exhibited flat-band potentials amenable to water oxidation reaction in a PEC cell. The 0.5 wt.% Cu-doped TiO2 thin film electrode exhibited an highest incident photon-to-current conversion efficiency (IPCE) of about 21%.

scholarly journals Effect of thickness on the optical properties of Gaas thin films

2013 ◽  
Vol 37 (1) ◽  
pp. 83-91 ◽  
Author(s):  
Chitra Das ◽  
Jahanara Begum ◽  
Tahmina Begum ◽  
Shamima Choudhury
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Band Gap ◽  
Optical Band Gap ◽  
Visible Region ◽  
Solar Spectrum ◽  
Band Gap Energy ◽  
Optical Parameters ◽  
Gap Energy

Effect of thickness on the optical and electrical properties of gallium arsenide (GaAs) thin films were studied. The films of different thicknesses were prepared by vacuum evaporation method (~10-4 Pa) on glass substrates at a substrate temperature of 323 K. The film thickness was measured in situ by a frequency shift of quartz crystal. The thicknesses were 250, 300 and 500 nm. Absorption spectrum of this thin film had been recorded using UV-VIS-NIR spectrophotometer in the photon wavelength range of 300 - 2500 nm. The values of some important optical parameters of the studied films (absorption coefficient, optical band gap energy and refractive index; extinction co-efficient and real and imaginary parts of dielectric constant) were determined using these spectra. Transmittance peak was observed in the visible region of the solar spectrum. Here transmittance showed better result when thicknesses were being increased. The optical band gap energy was decreased by the increase of thickness. The refractive index increased by increasing thickness while extinction co-efficient and real and imaginary part of dielectric constant decreased. DOI: http://dx.doi.org/10.3329/jbas.v37i1.15684 Journal of Bangladesh Academy of Sciences, Vol. 37, No. 1, 83-91, 2013

A novel theoretical model for the temperature dependence of band gap energy in semiconductors

2017 ◽  
Vol 50 (40) ◽  
pp. 40LT02 ◽  
Author(s):  
Peiji Geng ◽  
Weiguo Li ◽  
Xianhe Zhang ◽  
Xuyao Zhang ◽  
Yong Deng ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Temperature Dependence ◽  
Band Gap ◽  
Band Gap Energy ◽  
Gap Energy

Effect of Nb doping on morphology, crystal structure, optical band gap energy of TiO2 thin films

2014 ◽  
Vol 14 (3) ◽  
pp. 421-427 ◽  
Author(s):  
Deuk Yong Lee ◽  
Ju-Hyun Park ◽  
Young-Hun Kim ◽  
Myung-Hyun Lee ◽  
Nam-Ihn Cho
Keyword(s):  
Crystal Structure ◽  
Thin Films ◽  
Band Gap ◽  
Optical Band Gap ◽  
Band Gap Energy ◽  
Tio2 Thin Films ◽  
Gap Energy ◽  
Nb Doping

Particle size-band gap energy-catalytic properties relationship of PSE-CVD-derived Fe3O4 thin films

2018 ◽  
Vol 93 ◽  
pp. 427-435 ◽  
Author(s):  
Patrick Mountapmbeme Kouotou ◽  
Achraf El Kasmi ◽  
Ling-Nan Wu ◽  
Muhammad Waqas ◽  
Zhen-Yu Tian
Keyword(s):  
Thin Films ◽  
Particle Size ◽  
Band Gap ◽  
Catalytic Properties ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Relationship Of

scholarly journals Effect of Doping Concentration on the Optical Properties of Indium-Doped Gallium Arsenide Thin FILMS

2016 ◽  
Vol 40 (2) ◽  
pp. 179-186 ◽  
Author(s):  
Md Saiful Islam ◽  
Chitra Das ◽  
Mehnaz Sharmin ◽  
Kazi Md Amzad Hussain ◽  
Shamima Choudhury
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Band Gap ◽  
Doping Concentration ◽  
High Vacuum ◽  
Band Gap Energy ◽  
Crystal Thickness ◽  
Thermal Evaporation Method ◽  
Gap Energy ◽  
Indium Doping

Effects of indium doping (concentration 0.2, 0.3 and 0.4%) on the optical properties of GaAs thin films were studied. Thin films of 600 nm were grown onto chemically and ultrasonically cleaned glass substrate by thermal evaporation method in high vacuum (~10-4 Pa) at 50°C fixed substrate temperature. The samples were annealed for 15 minutes at a fixed temperature of 200°C. The thicknesses of films were being measured in situ by a quartz crystal thickness monitor during deposition. The transmittance and reflectance data were found using UV-VIS-NIR spectrophotometer in the photon wavelength range of 310 ~ 2500 nm. These data were utilized to compute the absorption coefficient, refractive index, extinction co-efficient and band gap energy of the studied films. Here transmittance was found 78 for 0.2% indium doping concentration. The band gap energy decreased with the increase of doping concentration.Journal of Bangladesh Academy of Sciences, Vol. 40, No. 2, 179-186, 2016

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

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