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

Fast Recovery of the High Work Function of Tungsten and Molybdenum Oxides via Microwave Exposure for Efficient Organic Photovoltaics

2014 ◽  
Vol 5 (11) ◽  
pp. 1871-1879 ◽  
Author(s):  
Maria Vasilopoulou ◽  
Anastasia Soultati ◽  
Panagiotis Argitis ◽  
Thomas Stergiopoulos ◽  
Dimitris Davazoglou
Keyword(s):  
Work Function ◽  
Organic Photovoltaics ◽  
Molybdenum Oxides ◽  
Fast Recovery ◽  
High Work Function ◽  
Microwave Exposure ◽  
Tungsten And Molybdenum Oxides ◽  
High Work

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

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.

Soluble Self-Doped Conducting Polymer Compositions with Tunable Work Function as Hole Injection/Extraction Layers in Organic Optoelectronics

2011 ◽  
Vol 123 (28) ◽  
pp. 6398-6401 ◽  
Author(s):  
Mi-Ri Choi ◽  
Tae-Hee Han ◽  
Kyung-Geun Lim ◽  
Seong-Hoon Woo ◽  
Dal Ho Huh ◽  
...  
Keyword(s):  
Work Function ◽  
Conducting Polymer ◽  
Hole Injection ◽  
Organic Optoelectronics

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).

INVARIANCE OF THE MOBILITY EDGE IN ANODIC TITANIUM OXIDES

1993 ◽  
Vol 07 (01n03) ◽  
pp. 361-364
Author(s):  
NACIR TIT ◽  
J. W. HALLEY ◽  
H. B. SHORE
Keyword(s):  
Oxygen Vacancies ◽  
Defect Density ◽  
Impurity Band ◽  
Scanning Tunneling ◽  
Titanium Oxides ◽  
Tunneling Microscopy ◽  
Mobility Edge ◽  
Band Formation ◽  
Gap States

We present a theoretical investigation to explain the electronic and optical properties of anodic rutile TiO2 thin films of different thicknesses (ranging from 5nm to 20nm). There is experimental evidence that the observed gap state at 0.7eV below the edge of conduction-band is due to an oxygen vacancy. For this reason, oxygen vacancies are used as defects in our model. A comparison of the calculated bulk-photoconductivity to photospectroscopy experiment reveals that the films have bulk-like transport properties with a bandgap Eg = 3.0eV. On the other hand, a fit of the surface density of states to the scanning tunneling microscopy (STM) experiment on the (001) surfaces has suggested a surface defect density of 5% of oxygen vacancies. To resolve this discrepancy, we calculated the dc-conductivity where localization effects are included. Our results show an impurity band formation at about pc = 9% of oxygen vacancies. We concluded that the studied films have defect densities below the threshold of impurity band formation. As a consequence the gap states seen in STM are localized (i.e: the oxygen vacancies are playing the role of trapping centers, deep levels) and the mobility edge is invariant.

Improvement of photo-induced negative bias stability of oxide thin film transistors by reducing the density of sub-gap states related to oxygen vacancies

2013 ◽  
Vol 102 (12) ◽  
pp. 122108 ◽  
Author(s):  
Kyoung-Seok Son ◽  
Joon Seok Park ◽  
Tae Sang Kim ◽  
Hyun-Suk Kim ◽  
Seok-Jun Seo ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Oxygen Vacancies ◽  
Oxide Thin Film ◽  
Negative Bias ◽  
Bias Stability ◽  
Gap States

scholarly journals In SituChemical Oxidation of UltrasmallMoOxNanoparticles in Suspensions

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Yun-Ju Lee ◽  
Diego Barrera ◽  
Kaiyuan Luo ◽  
Julia W. P. Hsu
Keyword(s):  
Work Function ◽  
Flexible Electronics ◽  
Low Cost ◽  
Chemical Oxidation ◽  
Large Area ◽  
Solution Deposition ◽  
Precise Control ◽  
Organic Optoelectronics ◽  
Continuous Tuning ◽  
Nanoparticle Suspensions

Nanoparticle suspensions represent a promising route toward low cost, large area solution deposition of functional thin films for applications in energy conversion, flexible electronics, and sensors. However, parameters such size, stoichiometry, and electronic properties must be controlled to achieve best results for the target application. In this report, we demonstrate that such control can be achieved viain situchemical oxidation ofMoOxnanoparticles in suspensions. Starting from a microwave-synthesized suspension of ultrasmall (d~2 nm)MoOxnanoparticles in n-butanol, we added H2O2at room temperature to chemically oxidize the nanoparticles. We systematically varied H2O2concentration and reaction time and found that they significantly affected oxidation state and work function ofMoOxnanoparticle films. In particular, we achieved a continuous tuning ofMoOxwork function from 4.4 to 5.0 eV, corresponding to oxidation of as-synthesizedMoOxnanoparticle (20% Mo6+) to essentially pure MoO3. This was achieved without significantly modifying nanoparticle size or stability. Such precise control ofMoOxstoichiometry and work function is critical for the optimization ofMoOxnanoparticles for applications in organic optoelectronics. Moreover, the simplicity of the chemical oxidation procedure should be applicable for the development of other transition oxide nanomaterials with tunable composition and properties.

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