Amorphous WO3 thin films designed as gigahertz/terahertz dielectric lenses

2021 ◽  
Author(s):  
Atef Qasrawi ◽  
Shatha Abu Alrub ◽  
Rana Daragme
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Energy Band ◽  
Cutoff Frequency ◽  
Dielectric Resonators ◽  
Excess Oxygen ◽  
Frequency Spectra ◽  
Wide Range ◽  
Light Signals ◽  
Dielectric Lenses

Abstract Herein, tungsten oxide thin films comprising excess oxygen are treated as optical resonator suitable for gigahertz/terahertz applications. WO 3 thin films which are prepared by the thermal evaporation technique under a vacuum pressure of 10 -5 mbar are structurally, compositionally and optically evaluated. The amorphous WO 3.33 films which showed high transparency permit electronic transitions within an indirect allowed energy band gap of 3.05 eV. The band gap comprised energy band tails of width of 190 meV. Four dominant dielectric resonators centered in the infrared (IR), visible (VIS) and ultraviolet (UV) ranges of light are detected. Analysis of the optical conductivity in accordance with the Drude-Lorentz approaches have shown that the drift mobility of free holes in this amorphous layer can be as large as 5.61 cm 2 /Vs an as low as 1.59 cm 2 /Vs when exposed to IR and UV light signals, respectively. In addition, the gigahertz/terahertz cutoff frequency ( ) spectra demonstrated values in the gigahertz frequency domain when exposed to IR light. Excitations with light signals in the VIS and UV spectral ranges allow values that extends from 0.7-40.0 THz. The wide range of tunability of the WO 3 dielectric resonators nominates them as dielectric lenses suitable for optical communications.

scholarly journals Optoelectronics applications of electrodeposited p- and n-type Al2Se3 thin films

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
A. A. Faremi ◽  
S. S. Oluyamo ◽  
O. Olubosede ◽  
I. O. Olusola ◽  
M. A. Adekoya ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Band Gap ◽  
Energy Band ◽  
Selenium Dioxide ◽  
Photoelectrochemical Cells ◽  
Energy Band Gap ◽  
Cathodic Deposition ◽  
Conductivity Type ◽  
P Type

Abstract In this paper, energy band gaps and electrical conductivity based on aluminum selenide (Al2Se3) thin films are synthesized electrochemically using cathodic deposition technique, with graphite and carbon as cathode and anode, respectively. Synthesis is done at 353 K from an aqueous solution of analytical grade selenium dioxide (SeO2), and aluminum chloride (AlCl2·7H2O). Junctions-based Al2Se3 thin films from a controlled medium of pH 2.0 are deposited on fluorine-doped tin oxide (FTO) substrate using potential voltages varying from 1,000 mV to 1,400 mV and 3 minutes −15 minutes respectively. The films were characterized for optical properties and electrical conductivity using UV-vis and photoelectrochemical cells (PEC) spectroscopy. The PEC reveals a transition in the conduction of the films from p-type to n-type as the potential voltage varies. The energy band gap reduces from 3.2 eV to 2.9 eV with an increase in voltage and 3.3 eV to 2.7 eV with increase in time. These variations indicate successful fabrication of junction-based Al2Se3 thin films with noticeable transition in the conductivity type and energy band gap of the materials. Consequently, the fabricated Al2Se3 can find useful applications in optoelectronic devices.

Energy Band Gap Shift of ZnS-ZnO Thin Films Grown by Pulsed Laser Deposition

2010 ◽  
Vol 404 (1) ◽  
pp. 186-191 ◽  
Author(s):  
J.-K. Chung ◽  
J. W. Kim ◽  
D. Do ◽  
S. S. Kim ◽  
T. K. Song ◽  
...  
Keyword(s):  
Thin Films ◽  
Pulsed Laser Deposition ◽  
Band Gap ◽  
Energy Band ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Zno Thin Films ◽  
Energy Band Gap

Band-Gap Engineering Based on Ti@ZnO Nanocolloids: Tunable Optical Properties

2014 ◽  
Vol 617 ◽  
pp. 161-165
Author(s):  
Chrystelle Neaime ◽  
Fabien Grasset ◽  
Tangi Aubert
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Uv Light ◽  
Sol Gel ◽  
Wide Band ◽  
Colloidal Solutions ◽  
Light Emitters ◽  
Wide Range ◽  
High Concentrations ◽  
Acoustic Wave Devices

One of the largest application areas of sol-gel chemistry is thin-film preparation. Using this approach, we started to synthesize M@ZnO colloidal solutions for the preparation of functional thin films. ZnO is a wide band-gap (3.37 eV) semiconductor with large exciton binding energy. In the bulk or in nanosized form, it could be used in a wide range of applications such as UV light emitters, spin functional devices, gas sensors, transparent electronics or surface acoustic wave devices. Since recently, the preparation of innovative functional M@ZnO materials by doping or functionalizing nanocolloids constitutes a new challenge. Using high concentrations of the different Ti@ZnO nanocolloids, we were able to prepare various functional colloidal solutions with tunable emission and thin films, such as red-luminescent Eu3+@ZnTiO3 or versatile ZnTiON colored nanomaterials.

scholarly journals Dependence on the Partial Pressure of Oxygen on the Shift in the Energy Band-gap of CdO Thin Films in the Visible Region

2001 ◽  
Vol 24 (1) ◽  
pp. 57-61 ◽  
Author(s):  
M. A. Grado-Caffaro ◽  
M. Grado-Caffaro ◽  
S. L. Sapienza
Keyword(s):  
Thin Films ◽  
Partial Pressure ◽  
Band Gap ◽  
Energy Band ◽  
Visible Region ◽  
Point Of View ◽  
Theoretical Point ◽  
Partial Pressure Of Oxygen ◽  
Energy Band Gap ◽  
Cdo Thin Films

In this paper, the dependence on the partial pressure of oxygen of the shift in the energy band-gap of CdO thin films for the visible region is investigated from the theoretical point of view on an experimental basis. In our analysis, the role played by the dependence of the carrier density upon the above pressure is emphasized.

scholarly journals ALD grown nanostructured ZnO thin films: Effect of substrate temperature on thickness and energy band gap

2016 ◽  
Vol 28 (4) ◽  
pp. 347-354 ◽  
Author(s):  
Javed Iqbal ◽  
Asim Jilani ◽  
P.M. Ziaul Hassan ◽  
Saqib Rafique ◽  
Rashida Jafer ◽  
...  
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Band Gap ◽  
Energy Band ◽  
Zno Thin Films ◽  
Energy Band Gap

Modulation of Energy Band Gap of ZnO Thin Films Grown by Pulsed Laser Deposition

2003 ◽  
Vol 764 ◽  
Author(s):  
Sang Yeol Lee ◽  
Yuan Li ◽  
Jang-Sik Lee ◽  
J. K. Lee ◽  
M. Nastasi ◽  
...  
Keyword(s):  
Thin Films ◽  
Pulsed Laser Deposition ◽  
Band Gap ◽  
Energy Band ◽  
Pulsed Laser ◽  
Processing Parameters ◽  
Laser Deposition ◽  
Energy Band Gap ◽  
Sapphire Substrates ◽  
Optical Energy Band Gap

AbstractZnCdO thin films were deposited on (001) sapphire substrates by pulsed laser deposition. Modulation of the energy band gap of ZnCdO was induced by changing the processing parameters. The optical energy band gap of ZnCdO thin films, measured by photoluminescence and transmittance, changed from 3.289 eV to 3.311 eV due to the variation of annealing temperatures. The change of the optical properties was attributed to the change of the stoichiometry of ZnxCd1-xO as illustrated by Rutherford backscattering spectroscopy.

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