scholarly journals Oxygen Vacancies Allow Tuning the Work Function of Vanadium Dioxide

2018 ◽  
Vol 5 (22) ◽  
pp. 1801033 ◽  
Author(s):  
Rongbin Wang ◽  
Takayoshi Katase ◽  
Ke‐Ke Fu ◽  
Tianshu Zhai ◽  
Jiacheng Yang ◽  
...  
Keyword(s):  
Work Function ◽  
Vanadium Dioxide ◽  
Oxygen Vacancies

scholarly journals Atomic Origin for Hydrogenation Promoted Bulk Oxygen Vacancies Removal in Vanadium Dioxide

2020 ◽  
Vol 11 (23) ◽  
pp. 10045-10051
Author(s):  
Bowen Li ◽  
Min Hu ◽  
Hui Ren ◽  
Changlong Hu ◽  
Liang Li ◽  
...  
Keyword(s):  
Vanadium Dioxide ◽  
Oxygen Vacancies ◽  
Bulk Oxygen

Physical mechanism of work of microwave devices cathodes with osmium

2021 ◽  
Vol 1 ◽  
pp. 22-34
Author(s):  
V. I. Kapustin ◽  
◽  
I. P. Li ◽  
S. O. Moskalenko ◽  
A. V. Shumanov ◽  
...  
Keyword(s):  
Work Function ◽  
Electron Energy ◽  
Optical Spectroscopy ◽  
Electron Spectroscopy ◽  
Oxygen Vacancies ◽  
Physical Mechanism ◽  
Surface States ◽  
Microwave Devices ◽  
Emission Properties ◽  
Donor Type

Emission properties of the traditional metal porous cathodes (MPC) are determined by oxygen vacancies in BaO crystallites and the surface located oxygen vacancies forms the acceptor type surface states in accordance with it take place the distorting of energy zones to up. In cathodes with osmium the osmium atoms are dissolved in BaO crystallites and then formed the donor type surface states in accordance with it take place the distorting of energy zones to down and the decreasing of work function. All investigations were made by using of optical spectroscopy, electron spectroscopy for chemistry analysis, spectroscopy of the characteristic electron energy loses.

Optimizing MIM Device Electrical Properties. Impact of Bottom Electrodes and High K Materials

2008 ◽  
Vol 1108 ◽  
Author(s):  
Marceline Bonvalot ◽  
Christophe Vallée ◽  
Emmanuel Gourvest ◽  
Corentin Jorel ◽  
Patrice Gonon
Keyword(s):  
Work Function ◽  
Electrode Material ◽  
Oxygen Vacancies ◽  
Bottom Electrode ◽  
Leakage Currents ◽  
Capacitance Density ◽  
High K ◽  
High K Materials ◽  
High Work ◽  
Mim Capacitors

AbstractHigh quality MIM capacitors with improved capacitance density, low leakage currents and linear C(V) behaviour are the object of active research, with potential applications in CMOS, BICMOS and bipolar technologies as filters, analog to digital converters and related radio-frequency operating devices. Several high-k materials (Ta2O5, HfO2, Y2O3, Al2O3-HfTiO, HfON-SiO2) have been put on trial as possible candidates for SiO2 substitution which is required by the aggressive downscaling of electronic devices. Among those, HfO2- based materials seem to offer promising properties, combining a high chemical stability with Si and a high k value. However, HfO2 shows a strong ability to favour charge defects such as oxygen vacancies, which in turn affect the intrinsic properties of devices such as threshold voltage or leakage currents. These oxygen vacancies are actually thought to accumulate in the vicinity of the electrode, thus forming an oxidized interfacial layer and inducing a significant voltage linearity degradation of MIM capacitors.In this work, it will be shown that this oxide layer thickness can be strongly minimized by using appropriate bottom electrode material. Indeed, high work function materials can efficiently prevent oxygen vacancies charge stocking on their surface. Several MIM devices have been prepared based on HfO2, Al2O3 and SrTiO3 as dielectric materials, and TiN, WSi2.7 and Pt as bottom electrode material. All these devices have been fully characterized in terms of materials properties and electrical behaviour. These results have been analysed and show that a reduced dielectric thickness is preferred to achieve high capacitance density, but is also responsible for voltage linearity degradation. High work function electrode material can help improve this degraded linear behaviour, thanks to the formation of a reduced interfacial oxygen trap layer thickness. Leakage currents seem to be deeply correlated with the morphological state of the dielectric material, an amorphous state being obviously more efficient to prevent current pathways through grain boundaries.All these results will be presented in detail and discussed with regards to different models proposed in the literature to account for these data.

Decrease in Work Function of Transparent Conducting ZnO Thin Films by Phosphorus Ion Implantation

2008 ◽  
Vol 8 (9) ◽  
pp. 4877-4880 ◽  
Author(s):  
Gi-Seok Heo ◽  
Sang-Jin Hong ◽  
Jong-Woon Park ◽  
Bum-Ho Choi ◽  
Jong-Ho Lee ◽  
...  
Keyword(s):  
Thin Films ◽  
Work Function ◽  
Oxygen Vacancies ◽  
Optical Transmittance ◽  
Zno Thin Films ◽  
Zno Films ◽  
Free Electrons ◽  
Electrical And Optical Properties ◽  
Transparent Conducting ◽  
Visible Wavelength Range

To confirm the possibility of engineering the work function of ZnO thin films, we have implanted phosphorus ions into ZnO thin films deposited by radio-frequency magnetron sputtering. The fabricated films show n-type characteristics. It is shown that the electrical and optical properties of those thin films vary depending sensitively on the ion dose and rapid thermal annealing time. Compared to as-deposited ZnO films, the work-function of phosphorus ion-implanted ZnO thin films is observed to be lower and decreases with increasing ion doses. It is likely that the zinc or oxygen vacancies are firstly filled with the implanted phosphorus ions. With further increased ions, free electrons are generated as Zn2+ sites are replaced by those ions or interstitial phosphorus ions increase at the lattice sites, the fermi level by which approaches the conduction band and thus the work function decreases. Those films exhibit the optical transmittance higher than 85% within the visible wavelength range (up to 800 nm).

Work Function Increase of Al-Doped ZnO Thin Films by B+ Ion Implantation

2007 ◽  
Vol 7 (11) ◽  
pp. 4077-4080 ◽  
Author(s):  
Sang-Jin Hong ◽  
Gi-Seok Heo ◽  
Jong-Woon Park ◽  
In-Hwan Lee ◽  
Bum-Ho Choi ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Work Function ◽  
Oxygen Vacancies ◽  
Defect Density ◽  
Transparent Conducting Oxide ◽  
Doping Profile ◽  
Ion Energy ◽  
Transparent Conducting ◽  
Azo Thin Film ◽  
Doped Zno

The work function of an Al-doped ZnO (AZO) thin film can be increased via B+ ion implantation from 3.92 eV up to 4.22 eV. The ion implantation has been carried out with the ion dose of 1 × 1016 cm−2 and ion energy of 5 keV. The resistance of the B+ implanted AZO films has been a bit raised, while their transmittance is slightly lowered, compared to those of un-implanted AZO films. These behaviors can be explained by the doping profile and the resultant band diagram. It is concluded that the coupling between the B+ ions and oxygen vacancies would be the main reason for an increase in the work function and a change in the other properties. We also address that the work function is more effectively alterable if the defect density of the top transparent conducting oxide layer can be controlled.

scholarly journals Evolution of Metallicity in Vanadium Dioxide by Creation of Oxygen Vacancies

2017 ◽  
Vol 7 (3) ◽  
Author(s):  
Zhen Zhang ◽  
Fan Zuo ◽  
Chenghao Wan ◽  
Aveek Dutta ◽  
Jongbum Kim ◽  
...  
Keyword(s):  
Vanadium Dioxide ◽  
Oxygen Vacancies

The Influence of Hydrogenation and Oxygen Vacancies on Molybdenum Oxides Work Function and Gap States for Application in Organic Optoelectronics

2012 ◽  
Vol 134 (39) ◽  
pp. 16178-16187 ◽  
Author(s):  
Maria Vasilopoulou ◽  
Antonios M. Douvas ◽  
Dimitra G. Georgiadou ◽  
Leonidas C. Palilis ◽  
Stella Kennou ◽  
...  
Keyword(s):  
Work Function ◽  
Oxygen Vacancies ◽  
Molybdenum Oxides ◽  
Organic Optoelectronics ◽  
Gap States

Surface reactions observed by photoemission electron microscopy (PEEM)

1992 ◽  
Vol 50 (1) ◽  
pp. 286-287
Author(s):  
H.H. Rotermund
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Work Function ◽  
Chemical Reactions ◽  
Reaction Diffusion ◽  
Dynamic Processes ◽  
Clean Surface ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces ◽  
Photoemission Electron

Chemical reactions at a surface will in most cases show a measurable influence on the work function of the clean surface. This change of the work function δφ can be used to image the local distributions of the investigated reaction,.if one of the reacting partners is adsorbed at the surface in form of islands of sufficient size (Δ>0.2μm). These can than be visualized via a photoemission electron microscope (PEEM). Changes of φ as low as 2 meV give already a change in the total intensity of a PEEM picture. To achieve reasonable contrast for an image several 10 meV of δφ are needed. Dynamic processes as surface diffusion of CO or O on single crystal surfaces as well as reaction / diffusion fronts have been observed in real time and space.

Conditions for atomic imaging of mullite

1989 ◽  
Vol 47 ◽  
pp. 418-419
Author(s):  
T. A. Epicier ◽  
G. Thomas
Keyword(s):  
Oxygen Vacancies ◽  
High Resolution Electron Microscopy ◽  
Ceramic Materials ◽  
Work Conditions ◽  
Real Space ◽  
Potential Candidate ◽  
Silicate Mineral ◽  
Resolution Electron ◽  
The Subject ◽  
Aluminium Silicate

Mullite is an aluminium-silicate mineral of current interest since it is a potential candidate for high temperature applications in the ceramic materials field.In the present work, conditions under which the structure of mullite can be optimally imaged by means of High Resolution Electron Microscopy (HREM) have been investigated. Special reference is made to the Atomic Resolution Microscope at Berkeley which allows real space information up to ≈ 0.17 nm to be directly transferred; numerous multislice calculations (conducted with the CEMPAS programs) as well as extensive experimental through-focus series taken from a commercial “3:2” mullite at 800 kV clearly show that a resolution of at least 0.19 nm is required if one wants to get a straightforward confirmation of atomic models of mullite, which is known to undergo non-stoichiometry associated with the presence of oxygen vacancies.Indeed the composition of mullite ranges from approximatively 3Al2O3-2SiO2 (referred here as 3:2-mullite) to 2Al2O3-1SiO2, and its structure is still the subject of refinements (see, for example, refs. 4, 5, 6).

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