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Wyszukujesz frazę "surface states" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Two-dimensional modeling of surface photovoltage in metal/insulator/n-GaN structure with cylindrical symmetry
Autorzy:
Matys, M
Powroznik, P
Kupka, D
Adamowicz, B
Powiązania:
https://bibliotekanauki.pl/articles/174326.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
surface photovoltage
gallium nitride
metal-insulator-semiconductor (MIS) structure
interface states
photodetector
Opis:
The rigorous numerical analysis of the surface photovoltage (SPV) versus excitation UV-light intensity (Φ), from 104 to 1020 photon/(cm2s) in a metal/insulator/n-GaN structure with a negative gate voltage (VG = –2 V) was performed using a finite element method. In the simulations we assumed a continuous U-shape density distribution function Dit(E) of the interface states and n-type doping concentration ND = 1016 cm–3. The SPV signal was calculated and compared in three different characteristic regions at the interface, namely i) under the gate centre, ii) near the gate edge and iii) between the gate and ohmic contact. We attributed the differences in SPV(Φ) dependences to the influence of the interface states in terms of the initial band bending and interface recombination controlled by the gate bias. The obtained results are useful for the design of GaN-based UV-radiation photodetectors.
Źródło:
Optica Applicata; 2013, 43, 1; 47-52
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A first-principle study of the effect of Fe/Al impurity defects on the surface wettability of dolomite
Autorzy:
Chen, Hong
Ao, Xianquan
Cao, Yang
Li, Cuiqin
Jiang, Chunyan
Powiązania:
https://bibliotekanauki.pl/articles/2146916.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
density functional theory
phosphate rock flotation
dolomite
surface wettability
density of states
Opis:
The presence of Fe and Al atoms in large quantities in phosphate ores can significantly affect the surface properties of the minerals during flotation. In this study, the effects of Fe/Al impurities on the adsorption of H2O molecules on dolomite, including the density of states (DOS), Mulliken bond group values, and charge groups, were investigated and the adsorption energy was analyzed using density functional theory. The results show that the adsorption of H2O molecules on perfect and Fe/Al-substituted dolomites is weak chemisorption, and the Fe and Al impurities weaken and enhance the adsorption capacity of H2O molecules, respectively. Therefore, the hydrophilicity of the dolomite surface increases in the following order: Fe-substituted dolomite < perfect dolomite < Al-substituted dolomite. The Mulliken charge and bond group analysis shows that the adsorption of H2O molecules on dolomite is primarily through the interaction between Ow and Ca atoms, where the d orbitals of Ca atoms provide charges for Ow atoms to form ionic bonds, which related to the poor electronegativity of Ca atoms and their weak valence electron binding ability. The DOS analysis shows that, during the adsorption of H2O molecules on dolomite, Mg and Al atoms have less influence on the dolomite surface, whereas Fe and Ca atoms undergo competitive adsorption, which inhibits the interaction between Ca atoms and H2O molecules on the dolomite surface.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 4; art. no. 150702
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
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