Enhancing Visible Light Photocatalysis with Hydrogenated Titanium Dioxide for Anti-Fouling Applications

MRS Advances ◽  
2018 ◽  
Vol 3 (53) ◽  
pp. 3181-3187 ◽  
Author(s):  
Safa Al Zaim ◽  
Aikifa Raza ◽  
Jin You Lu ◽  
Daniel Choi ◽  
Nicholas X. Fang ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Light Absorption ◽  
Titanium Substrate ◽  
Chemical Vapor ◽  
Ultra Violet ◽  
Visible Range ◽  
Hydrogen Dissociation ◽  
Pressure Chemical ◽  
The Impact ◽  
Titanium Substrates

ABSTRACTAnti-organic fouling performance of titanium dioxide (TiO2) can be enhanced by extending its light absorption and photocatalytic capability from ultra-violet to the visible range through hydrogenation. In this work, we aim at studying the impact of hydrogenation on the performance of both electron beam-deposited TiO2 thin films and hydrothermally grown TiO2 nanostructures on titanium substrates. Hydrogenation of these TiO2-deposited titanium substrates (TiO2/Ti) are achieved in relatively low-temperature low-pressure chemical vapor deposition chamber without any noble diatomic hydrogen dissociation catalyst, such as platinum. Our study shows that these hydrogenated TiO2/Ti have better light absorption ability and the titanium substrate itself serves as the active catalyst for hydrogen dissociation and diffusion. By applying hydrogenation to the TiO2 nanostructures, we can enhance photocatalytic performance by 50% through methylene blue degradation experiments. We have also evaluated the effect of hydrogenation on carrier density and mobility in TiO2/Ti. We recommend the hydrogenation of hydrothermally grown TiO2 nanostructure on titanium substrates for scalable photocatalytic applications.

Impact of In Situ NH3 pre-treatment of LPCVD SiN passivation on GaN HEMT performance

2022 ◽  
Author(s):  
Ding-Yuan Chen ◽  
Axel R Persson ◽  
Kai Hsin Wen ◽  
Daniel Sommer ◽  
Jan Gruenenpuett ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Low Pressure ◽  
Untreated Sample ◽  
Pressure Chemical ◽  
Gan Hemts ◽  
Pre Treatment ◽  
The Impact

Abstract The impact on the performance of GaN HEMTs of in situ ammonia (NH3) pre-treatment prior to the deposition of silicon nitride (SiN) passivation with low-pressure chemical vapor deposition is investigated. Three different NH3 pre-treatment durations (0, 3, and 10 minutes) were compared in terms of interface properties and device performance. A reduction of oxygen at the interface between SiN and epi-structure is detected by Scanning Transmission Electron Microscopy-Electron Energy Loss Spectroscopy measurements in the sample subjected to 10 minutes of pre-treatment. The samples subjected to NH3 pre-treatment show a reduced surface-related current dispersion of 9 % (compared to 16% for the untreated sample), which is attributed to the reduction of oxygen at the SiN/epi interface. Furthermore, NH3 pre-treatment for 10 minutes significantly improves the current dispersion uniformity from 14.5 % to 1.9 %. The reduced trapping effects result in a high output power of 3.4 W/mm at 3 GHz (compared to 2.6 W/mm for the untreated sample). These results demonstrate that the in situ NH3 pre-treatment before low-pressure chemical vapor deposition of SiN passivation is critical and can effectively improves the large-signal microwave performance of GaN HEMTs.

Atmospheric pressure chemical vapor deposition of titanium dioxide films from TiCl4

2004 ◽  
Vol 109 (1-3) ◽  
pp. 17-23 ◽  
Author(s):  
B. Arvan ◽  
A. Khakifirooz ◽  
R. Tarighat ◽  
S. Mohajerzadeh ◽  
A. Goodarzi ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Chemical Vapor ◽  
Titanium Dioxide Films ◽  
Pressure Chemical

Mechanical stress of the electrical performance of polycrystalline-silicon resistors

2001 ◽  
Vol 16 (9) ◽  
pp. 2579-2582 ◽  
Author(s):  
N. Nakabayashi ◽  
H. Ohyama ◽  
E. Simoen ◽  
M. Ikegami ◽  
C. Claeys ◽  
...  
Keyword(s):  
Mechanical Stress ◽  
Polycrystalline Silicon ◽  
Chemical Vapor ◽  
Silicon Wafers ◽  
External Stress ◽  
Electrical Performance ◽  
Structural Differences ◽  
Pressure Chemical ◽  
Si Films ◽  
The Impact

Results are presented of a study on the mechanical stress dependence of the resistance of polycrystalline silicon (Poly-Si) films doped with different atomic species. Two types of Poly-Si film implanted with boron and phosphorus ions were studied, namely, B-doped films of 400 nm and P-doped films of 250 nm thickness, which were deposited by low-pressure chemical vapor deposition at 620 °C on thermally oxidized silicon wafers. The film doping was done by ion implantation at 50 keV, with a dose of boron and phosphorus of 2 × 1014 and 5.3 × 1014 cm−2, respectively. The Poly-Si films were annealed in a N2 ambient at 1000 °C for 20 min to activate the implanted atoms. A controlled amount of external stress was applied to the silicon wafers to study the impact on the electrical performance of the implanted Poly-Si resistors. The resistance of the B-doped Poly-Si films is shown to increase by the mechanical stress, while the resistance of the P-implanted Poly-Si films remained unchanged. It is concluded that this difference is related to the structural differences between Poly-Si films implanted with boron and phosphorus, respectively.

EFFECT OF Al DOPING CONCENTRATION ON MICROSTRUCTURE, PHOTOELECTRIC PROPERTIES AND DOPED MECHANISM OF AZO FILMS

2014 ◽  
Vol 21 (03) ◽  
pp. 1450040 ◽  
Author(s):  
YING XU ◽  
YANQING CAI ◽  
LINYAN HOU ◽  
PENGHUA MA
Keyword(s):  
Thin Films ◽  
Doping Concentration ◽  
Chemical Vapor ◽  
Optical Transmittance ◽  
Visible Range ◽  
Zno Films ◽  
Al Doping ◽  
Limit Value ◽  
Photoelectric Properties ◽  
Pressure Chemical

Al doped ZnO (AZO) thin films were deposited on a glass substrate by atmospheric pressure chemical vapor deposition (APCVD) method. Effect of Al doping concentration on microstructure, photoelectric properties and doped mechanism of AZO thin films were investigated. The analysis results revealed that the structural properties of the films possessed crystalline structure with a preferred (002) orientation. The best crystallization quality and minimum electrical resistivity was obtained at 5 at.% Al doped films and the minimum resistivity was 6.6 × 10-4 Ω ⋅ cm. Uniform granular grains were observed on the surface of AZO films, and the average optical transmittance was above 80% in the visible range. The doped mechanism of AZO films was analyzed as follows. With Al doping in ZnO films, AlZn substitute and Ali interstice were produced, which decreased the resistivity of films. While after the limit value and with the continuing increase of Al doping concentration, free electrons were consumed and the resistivity of films increased.

Rapid densification of borophosphosilicate glass

1989 ◽  
Vol 67 (4) ◽  
pp. 174-178 ◽  
Author(s):  
Lynnette D. Madsen ◽  
Jacques S. Mercier
Keyword(s):  
Flow Behavior ◽  
Chemical Vapor ◽  
Peak Height ◽  
Densification Temperature ◽  
Device Processing ◽  
Pressure Chemical ◽  
Rapid Thermal Annealer ◽  
Wet Etch ◽  
The Impact ◽  
Borophosphosilicate Glass

The effect of densification, using a rapid thermal annealer, on properties of low pressure chemical vapor deposited borophosphosilicate glass films (4 wt.% B, 4 wt.% P) has been investigated. After densification, the wet etch rate of the films decreased by a factor of 12, while the infrared Si–O band peak height increased by 10%. Application of these findings to process monitoring and the impact of densification on subsequent processing have been examined. Results show that a single densification cycle at 950 °C/20 s induces glass flow behavior. Furthermore, for densification cycles from 500 to 1000 °C for 20 s followed by a fusion cycle of 1100 °C/20 s, densification temperature has no effect on the smoothing of glass over step structures. However, for contact sidewalls a densification cycle of at least 700 °C/20 s is required for sufficient tapering of the sharp corner. An optimal densification cycle for device processing was determined to be 800 °C/20 s.

Impact of surface hydroxylation in MgO-/SnO-nanocluster modified TiO2 anatase (101) composites on visible light absorption, charge separation and reducibility.

2017 ◽  
Author(s):  
Michael Nolan ◽  
Stephen Rhatigan
Keyword(s):  
Metal Oxide ◽  
Visible Light ◽  
Light Absorption ◽  
Charge Separation ◽  
Density Functional ◽  
Visible Range ◽  
Hydroxyl Groups ◽  
Visible Light Absorption ◽  
Tio2 Anatase ◽  
The Impact

Surface modification with metal oxide nanoclusters has emerged as a candidate for the enhancement of the photocatalytic activity of titanium dioxide. An increase in visible light absorption and the suppression of charge carrier recombination are necessary to improve the efficiency. We have studied Mg<sub>4</sub>O<sub>4</sub> and Sn<sub>4</sub>O<sub>4</sub> nanoclusters modifying the (101) surface of anatase TiO<sub>2</sub> using density functional theory corrected for on-site Coulomb interactions (DFT + U). Such studies typically focus on the pristine surface, free of the point defects and surface hydroxyls present in real surfaces. We have also examined the impact of partial hydroxylation of the anatase surface on a variety of outcomes such as nanocluster adsorption, light absorption, charge separation and reducibility. Our results indicate that the modifiers adsorb strongly at the surface, irrespective of the presence of hydroxyl groups, and that modification extends light absorption into the visible range while enhancing UV activity. Our model for the excited state of the heterostructures demonstrates that photoexcited electrons and holes are separated onto the TiO<sub>2</sub> surface and metal oxide nanocluster respectively. Comparisons with bare TiO<sub>2</sub> and other TiO<sub>2</sub>-based photocatalyst materials are presented throughout.<br>

Impact of the Inhomogenous Structure of Polysilicon TFT's Active Layer on the Electrostatic Potential Distribution

2013 ◽  
Vol 685 ◽  
pp. 352-356
Author(s):  
Hadjira Tayoub ◽  
Asmaa Bensmain ◽  
Baya Zebentout ◽  
Zineb Benamara
Keyword(s):  
Active Layer ◽  
Electrostatic Potential ◽  
Polycrystalline Silicon ◽  
Silicon Film ◽  
Chemical Vapor ◽  
Transfer Characteristics ◽  
Vapor Deposition Technique ◽  
Pressure Chemical ◽  
The Impact ◽  
Polycrystalline Silicon Film

Recently polycrystalline silicon (pc-Si) thin film transistors (TFT’s) have emerged as the devices of choice for many applications. The TFTs made of a thin un-doped polycrystalline silicon film deposited on a glass substrate by the Low Pressure Chemical Vapor Deposition technique LPCVD have limits in the technological process to the temperature < 600°C. The benefit of pc-Si is to make devices with large grain size. Unfortunately, according to the conditions during deposition, the pc-Si layers can consist of a random superposition of grains of different sizes, where grains boundaries parallels and perpendiculars appear. In this paper, the transfer characteristics IDS-VGS are simulated by solving a set of two-dimensional (2D) drift-diffusion equations together with the usual density of states (DOS: exponential band tails and Gaussian distribution of dangling bonds) localized at the grains boundaries. The impact of thickness of the active layer on the distribution of the electrostatic potential and the effect of density of intergranular traps states on the TFT’s transfer characteristics IDS-VGS have been also investigated.

Impact of surface hydroxylation in MgO-/SnO-nanocluster modified TiO2 anatase (101) composites on visible light absorption, charge separation and reducibility.

2017 ◽  
Author(s):  
Michael Nolan ◽  
Stephen Rhatigan
Keyword(s):  
Metal Oxide ◽  
Visible Light ◽  
Light Absorption ◽  
Charge Separation ◽  
Density Functional ◽  
Visible Range ◽  
Hydroxyl Groups ◽  
Visible Light Absorption ◽  
Tio2 Anatase ◽  
The Impact

Surface modification with metal oxide nanoclusters has emerged as a candidate for the enhancement of the photocatalytic activity of titanium dioxide. An increase in visible light absorption and the suppression of charge carrier recombination are necessary to improve the efficiency. We have studied Mg<sub>4</sub>O<sub>4</sub> and Sn<sub>4</sub>O<sub>4</sub> nanoclusters modifying the (101) surface of anatase TiO<sub>2</sub> using density functional theory corrected for on-site Coulomb interactions (DFT + U). Such studies typically focus on the pristine surface, free of the point defects and surface hydroxyls present in real surfaces. We have also examined the impact of partial hydroxylation of the anatase surface on a variety of outcomes such as nanocluster adsorption, light absorption, charge separation and reducibility. Our results indicate that the modifiers adsorb strongly at the surface, irrespective of the presence of hydroxyl groups, and that modification extends light absorption into the visible range while enhancing UV activity. Our model for the excited state of the heterostructures demonstrates that photoexcited electrons and holes are separated onto the TiO<sub>2</sub> surface and metal oxide nanocluster respectively. Comparisons with bare TiO<sub>2</sub> and other TiO<sub>2</sub>-based photocatalyst materials are presented throughout.<br>

Correlation of Performance and Hot Carrier Stress Reliability of Polycrystalline Silicon Thin-Film Transistors With Substrates and Substrate Coating

1998 ◽  
Vol 508 ◽  
Author(s):  
Y. Z. Wang ◽  
O. O. Awadelkarim
Keyword(s):  
Coating Thickness ◽  
Chemical Vapor ◽  
Fused Silica ◽  
Silicon Thin Film ◽  
Hot Carrier ◽  
Coated Glass ◽  
Glass Substrates ◽  
Hot Carrier Stress ◽  
Pressure Chemical ◽  
The Impact

AbstractWe report on the performance and hot carrier stress (HCS) reliability of n-channel poly-Si TFTs fabricated on bare or SiO2-coated low-alkali glass, or fused silica substrates. Low-pressure chemical vapor deposited (LPCVD) SiO2 films with different thicknesses are used as impurity diffusion barrier layers. We have found that the performance and HCS reliability of n-TFTs on the SiO2-coated glass are superior to those of n-TFTs on bare glass, and comparable to those of TFTs on fused silica. We also explore the impact of the SiO2 coating thickness on the performance and HCS reliability of the TFTs. The HCS reliability of the TFTs on SiO2-coated glass substrates is observed to depend on the SiO2 coating thickness. This is explained in terms of a phenomenological model which involves impurity and grain boundary traps.

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