2 results
Search Results
Now showing 1 - 2 of 2
Article Citation - WoS: 3Citation - Scopus: 4Effects of Ge Substrate on the Structural and Optical Conductivity Parameters of Bi2o3< Thin Films(Elsevier Gmbh, 2019) Alharbi, S. R.; Qasrawi, A. F.In this article the structural, optical and dielectric properties of a 200 nm thick Bi2O3 thin films which are deposited onto amorphous germanium substrate are reported. Both of the Ge and Bi2O3 thin films are prepared by the thermal evaporation technique under vacuum pressure of 10 s mbar. Bi2O3 thin films are found to prefer the monoclinic nature of structure with larger values of microstrain, dislocation density, stacking faults and smaller grain sizes upon replacement of the glass substrate by germanium. Optically, significant redshift in the energy band gap is observed when the films are grown onto Ge. The Ge/Bi2O3 heterojunctions exhibit a conduction and valence band offsets of value of 0.81 and 1.38 eV, respectively. In addition to the enhancement in the dielectric constant near the IR region, the Drude-Lorentz modeling of the Ge/Bi2O3 heterojunctions has shown remarkable effect of the Ge substrate on the optical conductivity parameters of Bi2O3. Particularly, the drift mobility increased by about one order of magnitude, the free hole density decreased by (similar to)24 times and the plasmon frequency ranges extended from 5.21 to 11.0 GHz to 2.59-12.80 GHz when germanium substrate is used. The optical features of the heterojunction nominate it for visible light communication technology.Article Citation - WoS: 9Citation - Scopus: 9Optical Dynamics in the Ag/Α-ga2< Layer System(Elsevier Sci Ltd, 2018) Alharbi, S. R.; Qasrawi, A. F.In this work, thin films of Ga2S3 are deposited onto 150 nm thick transparent Ag substrate by the physical vapor deposition technique under vacuum pressure of 10(-5) mbar. The films are studied by the X-ray diffraction and optical spectrophotometry techniques. It is found that the Ag substrate induced the formation of the monoclinic alpha-Ga2S3 polycrystals. The transparent Ag substrate also changed the preferred optical transition in Ga2S3 from direct to indirect It also increased the light absorption by 79 and 23 times at incident light energies of 2.01 and 2.48 eV, respectively. In addition, a red shift in all types of optical transitions is observed. Some the extended energy band tails of Ag appears to form interbands in the band gap of Ga2S3. These interbands strongly attenuated the dielectric and optical conduction parameters. Particularly, an enhancement in the dielectric constant values and response to incident electromagnetic field is observed. The Drude-Lorentz modeling of this interface has shown that the free carrier density, drift mobility, plasmon frequency and reduced electron-plasmon frequency in Ga2S3 increases when the Ag substrate replaced the glass or other metals like Yb, Al and Au. The nonlinear optical dynamics of the Ag/Ga2S3 are promising as they indicate the applicability of this interface for optoelectronic applications.
