Hydrogen-Related Donors in Silicon: Centers with Negative Electronic Correlation Energy

2005 ◽  
Vol 108-109 ◽  
pp. 229-234 ◽  
Author(s):  
Yurii M. Pokotilo ◽  
Alla N. Petukh ◽  
Valentin V. Litvinov ◽  
B.G. Tsvirko
Keyword(s):  
Fermi Level ◽  
Room Temperature ◽  
Correlation Energy ◽  
Electronic Correlation ◽  
Equilibrium Configurations ◽  
Double Electron ◽  
Related Donor ◽  
Minority Carriers ◽  
Double Hydrogen ◽  
Electron Occupation

The transformation of the shallow hydrogen-related donors, which have been formed in the silicon samples by irradiation of the low energy (300 keV) protons and following heat treatment under 350 0С or 450 0С was investigated. The experiment was carried out on Ag-Mo-Si Shottky diodes and diodes with shallow p+-n-junction. The concentration and distribution of these donors were defined by C-V-method at 1.2 MHz frequency. Using temperature dependence of equilibrium electron concentration it was established, that the hydrogen-related donors were charged controlled centers with negative electronic correlation energy (U<0). The transformation between both equilibrium configurations of the double hydrogen-related donor takes place when value of the Fermi level is arranged near Ec-0.30 eV. It was revealed that the donor transformation from neutral into double charged state have been stimulated by minority carriers trapping under room temperature when Fermi level was higher then level of the double electron occupation E(0/++)= Ec-0.30 eV.

Electronic Structure Benchmark Calculations of Inorganic and Biochemical Carboxylation Reactions

2018 ◽  
Author(s):  
Oscar A. Douglas-Gallardo ◽  
David A. Sáez ◽  
Stefan Vogt-Geisse ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Electronic Structure ◽  
Chemical Reactions ◽  
Density Functional ◽  
Correlation Energy ◽  
Electronic Energy ◽  
Basis Sets ◽  
Electronic Correlation ◽  
Correct Description ◽  
Carbon Dioxide Co2 ◽  
High Level

<div><div><div><p>Carboxylation reactions represent a very special class of chemical reactions that is characterized by the presence of a carbon dioxide (CO2) molecule as reactive species within its global chemical equation. These reactions work as fundamental gear to accomplish the CO2 fixation and thus to build up more complex molecules through different technological and biochemical processes. In this context, a correct description of the CO2 electronic structure turns out to be crucial to study the chemical and electronic properties associated with this kind of reactions. Here, a sys- tematic study of CO2 electronic structure and its contribution to different carboxylation reaction electronic energies has been carried out by means of several high-level ab-initio post-Hartree Fock (post-HF) and Density Functional Theory (DFT) calculations for a set of biochemistry and inorganic systems. We have found that for a correct description of the CO2 electronic correlation energy it is necessary to include post-CCSD(T) contributions (beyond the gold standard). These high-order excitations are required to properly describe the interactions of the four π-electrons as- sociated with the two degenerated π-molecular orbitals of the CO2 molecule. Likewise, our results show that in some reactions it is possible to obtain accurate reaction electronic energy values with computationally less demanding methods when the error in the electronic correlation energy com- pensates between reactants and products. Furthermore, the provided post-HF reference values allowed to validate different DFT exchange-correlation functionals combined with different basis sets for chemical reactions that are relevant in biochemical CO2 fixing enzymes.</p></div></div></div>

scholarly journals Room Temperature Processed Double Electron Transport Layers for Efficient Perovskite Solar Cells

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 329
Author(s):  
Wen Huang ◽  
Rui Zhang ◽  
Xuwen Xia ◽  
Parker Steichen ◽  
Nanjing Liu ◽  
...  
Keyword(s):  
Solar Cells ◽  
Electron Transport ◽  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Room Temperature ◽  
Deposition Time ◽  
Power Conversion ◽  
Perovskite Solar Cells ◽  
Electron Transport Layer ◽  
Double Electron

Zinc Oxide (ZnO) has been regarded as a promising electron transport layer (ETL) in perovskite solar cells (PSCs) owing to its high electron mobility. However, the acid-nonresistance of ZnO could destroy organic-inorganic hybrid halide perovskite such as methylammonium lead triiodide (MAPbI3) in PSCs, resulting in poor power conversion efficiency (PCE). It is demonstrated in this work that Nb2O5/ZnO films were deposited at room temperature with RF magnetron sputtering and were successfully used as double electron transport layers (DETL) in PSCs due to the energy band matching between Nb2O5 and MAPbI3 as well as ZnO. In addition, the insertion of Nb2O5 between ZnO and MAPbI3 facilitated the stability of the perovskite film. A systematic investigation of the ZnO deposition time on the PCE has been carried out. A deposition time of five minutes achieved a ZnO layer in the PSCs with the highest power conversion efficiency of up to 13.8%. This excellent photovoltaic property was caused by the excellent light absorption property of the high-quality perovskite film and a fast electron extraction at the perovskite/DETL interface.

Fermi level pinning or semiconductor electrodes in aqueous and non aqueous electrolytes: influence of the modification of the electrode surface

1989 ◽  
Vol 67 (3) ◽  
pp. 382-388 ◽  
Author(s):  
O. Savadogo
Keyword(s):  
Fermi Level ◽  
Acidic Medium ◽  
Open Circuit ◽  
Flat Band ◽  
Flat Band Potential ◽  
Fermi Level Pinning ◽  
Material Surfaces ◽  
Electrolyte Interface ◽  
Semiconductor Electrodes ◽  
Minority Carriers

Modification of several semiconductors material surfaces with H4SiW12O40•nH2O have been carried out to produce an increase in the open circuit photopotential at the semiconductor/electrolyte interface (Voc) without changing the flat-band potential. The augmentation of Voc is shown to be attributed to a decrease of the minority carriers recombination at the semiconductor/electrolyte interface along with the suppression of Fermi level pinning. The enhancement of Voc and the electrocatalytic activity of the hydrogen evolution reaction in acidic medium of the derivatized electrodes is attributed to the Fermi level unpinning. Keywords: photoelectrodes, photoelectrocatalysis, pinning, modification improvement.

The Dependence of the Magnetic Properties of GaMnN on Codoping by Mg and Si

2004 ◽  
Vol 834 ◽  
Author(s):  
Mason J. Reed ◽  
M. Oliver Luen ◽  
Meredith L. Reed ◽  
Salah M. Bedair ◽  
Fevzi Erdem Arkun ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Fermi Level ◽  
Energy Band ◽  
Room Temperature ◽  
Dopant Concentration ◽  
Room Temperature Ferromagnetism ◽  
Chemical Vapor ◽  
Material System ◽  
Si Doped ◽  
Mg Doped

ABSTRACTThe magnetic properties of GaMnN, grown by metalorganic chemical vapor deposition, depend on the addition of dopants; where undoped materials are ferromagnetic, and n -type (Si-doped) and p -type (Mg-doped) films are either ferromagnetic or paramagnetic depending on dopant concentration. The ferromagnetism of this material system seems correlated to Fermi level position, and is observed only when the Fermi level is within or close to the Mn energy band. This allows ferromagnetism-mediating carriers to be present in the Mn energy band. The current results exclude precipitates or clusters as the origin of room temperature ferromagnetism in GaMnN.

Formation of the yttrium/germanium interface: Fermi-level pinning and intermixing at room temperature

2012 ◽  
Vol 100 (9) ◽  
pp. 092110 ◽  
Author(s):  
Z. Q. Liu ◽  
W. K. Chim ◽  
S. Y. Chiam ◽  
J. S. Pan ◽  
C. M. Ng
Keyword(s):  
Fermi Level ◽  
Room Temperature ◽  
Fermi Level Pinning
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