Experimental and Theoretical Studies of the Si(100)/SiO2 Interface Formed by Wet and Dry Oxidation

2002 ◽  
Vol 747 ◽  
Author(s):  
A. Roy Chowdhuri ◽  
Dong-Un Jin ◽  
C. G. Takoudis
Keyword(s):  
Optical Model ◽  
Oxide Thickness ◽  
Longitudinal Optical ◽  
Process Conditions ◽  
Silicon Oxides ◽  
Different Temperatures ◽  
Interfacial Strain ◽  
Asymmetric Stretch ◽  
Experimental And Theoretical Studies ◽  
Different Thickness

ABSTRACTInterfacial strain and substoichiometric silicon oxides are the two principal causes that result in the redshift of the transverse and longitudinal optical phonons of the asymmetric stretch of O in the Si-O-Si bridging bond of thermal SiO2 with decreasing oxide thickness. Analyses to comprehend these effects, therefore, require consideration of both strain and interfacial substoichiometry. A method to isolate the contributions of strain and suboxide content towards the observed shifts is proposed. The procedure, which utilizes simple optical model and effective medium approximation, allows estimation of the average strain and suboxide concentration in films of different thickness. Analyses of oxides formed at two different temperatures (550 and 700°C) with dry and wet oxygen reveal how process conditions affect the interface properties.

Scalability of MOCVD-deposited Hafnium Oxide

2003 ◽  
Vol 765 ◽  
Author(s):  
S. Van Elshocht ◽  
R. Carter ◽  
M. Caymax ◽  
M. Claes ◽  
T. Conard ◽  
...  
Keyword(s):  
Hafnium Oxide ◽  
Interfacial Layer ◽  
Gate Dielectric ◽  
Deposition Process ◽  
Oxide Thickness ◽  
Process Conditions ◽  
Primary Concern ◽  
Gate Electrode ◽  
K Value ◽  
High K

AbstractBecause of aggressive downscaling to increase transistor performance, the physical thickness of the SiO2 gate dielectric is rapidly approaching the limit where it will only consist of a few atomic layers. As a consequence, this will result in very high leakage currents due to direct tunneling. To allow further scaling, materials with a k-value higher than SiO2 (“high-k materials”) are explored, such that the thickness of the dielectric can be increased without degrading performance.Based on our experimental results, we discuss the potential of MOCVD-deposited HfO2 to scale to (sub)-1-nm EOTs (Equivalent Oxide Thickness). A primary concern is the interfacial layer that is formed between the Si and the HfO2, during the MOCVD deposition process, for both H-passivated and SiO2-like starting surfaces. This interfacial layer will, because of its lower k-value, significantly contribute to the EOT and reduce the benefit of the high-k material. In addition, we have experienced serious issues integrating HfO2 with a polySi gate electrode at the top interface depending on the process conditions of polySi deposition and activation anneal used. Furthermore, we have determined, based on a thickness series, the k-value for HfO2 deposited at various temperatures and found that the k-value of the HfO2 depends upon the gate electrode deposited on top (polySi or TiN).Based on our observations, the combination of MOCVD HfO2 with a polySi gate electrode will not be able to scale below the 1-nm EOT marker. The use of a metal gate however, does show promise to scale down to very low EOT values.

Synthesis of Polyurethane Dendrimers and Transfer Properties of Dye

2013 ◽  
Vol 457-458 ◽  
pp. 65-71
Author(s):  
Jing Ru Jia
Keyword(s):  
Methyl Orange ◽  
Phase Transfer ◽  
Raw Materials ◽  
Toluene Diisocyanate ◽  
Polymerization Process ◽  
Process Conditions ◽  
Addition Polymerization ◽  
Different Temperatures ◽  
The Difference ◽  
Transfer Properties

The polyfunctional organic compounds 2- hydroxymethyl -1,4- butanediol (trihydric alcohol) and toluene diisocyanate -2, 4- diisocyanate (TDI) were taken as the raw materials in this study. A polyurethane dendrimer was synthesized by utilizing the difference in the reaction activity of two isocyanate groups of TDI at different temperatures. The polymerization process conditions were studied. The addition polymerization of para-position NCO groups occurred at 50 °C, and that of ortho NCO groups occurred at 90 °C. According to the structure of the dendrimer synthesized, methyl orange was used as the guest molecule. Consequently, the aqueous methyl orange showed a phase transfer. With the increase of dendrimer concentration, the transfer rate of methyl orange increased.

EFFECTS OF QUANTUM CONFINEMENT ON LOW FREQUENCY NOISE IN δ-DOPED GaAs STRUCTURES GROWN BY MBE

2002 ◽  
Vol 02 (01) ◽  
pp. L37-L45
Author(s):  
X. Y. CHEN ◽  
P. M. KOENRAAD
Keyword(s):  
Quantum Confinement ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Free Carriers ◽  
In Doping ◽  
Three Samples ◽  
Different Temperatures ◽  
Lower Magnitude ◽  
Different Thickness

Low frequency noise (LFN) was measured in δ-doped GaAs structures in which the free carriers are confined to a 2-dimensional plane. Three samples grown at different temperatures, resulting in doping layers of a different thickness, are used to study the effects of quantum confinement on the LFN. We observed both 1/f noise and generation-recombination noise components. We find that a stronger quantum confinement results in a bigger Hall mobility and a lower magnitude of the 1/f noise.

scholarly journals Broadband terahertz absorber based on dispersion-engineered catenary coupling in dual metasurface

Nanophotonics ◽  
2018 ◽  
Vol 8 (1) ◽  
pp. 117-125 ◽  
Author(s):  
Ming Zhang ◽  
Fei Zhang ◽  
Yi Ou ◽  
Jixiang Cai ◽  
Honglin Yu
Keyword(s):  
Optical Model ◽  
Dispersion Management ◽  
Bandwidth Extension ◽  
Limited Bandwidth ◽  
Terahertz Absorber ◽  
Simple Strategy ◽  
Management Ability ◽  
Potential Applications ◽  
Resolution Imaging ◽  
Different Thickness

AbstractTerahertz (THz) absorbers have attracted considerable attention due to their potential applications in high-resolution imaging systems, sensing, and imaging. However, the limited bandwidth of THz absorbers limits their further applications. Recently, the dispersion management of metasurfaces has become a simple strategy for the bandwidth extension of THz devices. In this paper, we used the capability of dispersion management to extend the bandwidth of THz absorbers. As a proof-of-concept, a dual metasurface-based reflective device was proposed for broadband near-unity THz absorber, which was composed of two polarization-independent metasurfaces separated from a metallic ground by dielectric layers with different thickness. Benefiting from the fully released dispersion management ability in adjusting the dimensions of the metasurfaces, we obtained an absorbance above 90% in the frequency range from 0.52 to 4.4 THz and the total thickness for the bandwidth approaching the theoretical Rozanov limit. The experimental results verified the ability of dispersion management in designing broadband absorbers and the performance of the designed absorber. The underlying physical mechanism of dispersion management was interpreted in the general equivalent circuit theory and transmission line model. In addition, the catenary optical model was used to further interpret the physics behind this dual metasurface. Moreover, we found that the alignment deviations between the dual metasurface had little impact on the performance of the designed absorber, which indicates that the dual-metasurface does not require center alignment and is easy to be fabricated. The results of this work could broaden the application areas of THz absorbers.

Effect of Drying on Porous Characteristics of Orange Peel

2016 ◽  
Vol 12 (9) ◽  
pp. 921-928 ◽  
Author(s):  
Cansu Tamer ◽  
Asli Isci ◽  
Naciye Kutlu ◽  
Ozge Sakiyan ◽  
Serpil Sahin ◽  
...  
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Orange Peel ◽  
Sem Analysis ◽  
Shrinkage Porosity ◽  
Process Conditions ◽  
Third Order ◽  
Strong Negative Correlation ◽  
Different Temperatures

Abstract The purpose of the study was to determine the effects of different temperatures (40, 50 and 60 °C) and air velocities (1 and 2 m/s) on shrinkage, porosity, pore size distribution, color and microstructure of orange peel. Empirical models were also proposed to predict shrinkage and porosity as a function of moisture. A strong negative correlation was determined between moisture and shrinkage. Air temperature had no significant impact on the final shrinkage and porosity values. During drying, porosity of the samples first increased until a critical value, at which point further decrease in moisture resulted in collapse of pores. The porosity of the orange peel was correlated with moisture by a third-order polynomial. Pore size distribution curve of raw sample showed two major peaks, a wider and a sharper peak at around 19.8 and 7.18 μm, respectively. After drying, the peaks became shorter and the curve shifted to the left, indicating that the amount of pores and their diameter decreased. The SEM analysis revealed that at extreme process conditions, the orange peel surface was cracked and the characteristic distribution of the waxy components was obstructed.

On the DIBL Reduction Effect of Short Channel Carbon Nanotube Field Effect Transistors

2016 ◽  
Vol 6 (4) ◽  
pp. 1514
Author(s):  
Khial Aicha ◽  
Rechem Djamil ◽  
Azizi Chrifa ◽  
Zaabat Mourad
Keyword(s):  
Field Effect ◽  
Field Effect Transistors ◽  
Liquid Nitrogen Temperature ◽  
Oxide Thickness ◽  
Short Channel ◽  
High K ◽  
Different Temperatures ◽  
Reduction Effect ◽  
High K Materials ◽  
Non Equilibrium Green’S Function

The Drain Induced Barrier Lowering (DIBL), in carbon Nanotubes-Fet (CNTFETS), is a challenging study that still needs investigation. Based on a numerical model, the Non-Equilibrium Green’s Function (NEGF) approach was applied to simulate the DIBL effect in CNTFETS. In this study,  the effect of the length gate ranging from 10 to 30 nm, for different temperatures (77K, 15K, 300K and 400K) on the DIBL was investigated. Then the variation of DIBL effect as a function of the nanotubes diameter varying over the following chiralities: (13, 0), (16, 0), (19, 0), (23, 0) and (25, 0) was undertaken. Afterworlds, we conducted the variation of DIBL impact as a function of the oxide thickness with the values: 1.5 nm, 3 nm, 4.5 nm, 6 nm and 7 nm. Moreover, the DIBL effect was carried at depending upon the high-k materials such as:  SiO_2, HfO_2, ZrO_2, 〖Ta〗_2 O_2 and TiO_2. Finally, a conclusion is made basing at the different findings which revealed that the best reduce of DIBL impact was recorded under a liquid Nitrogen temperature of 77 K.

Photoreflectance Characterization of InGaAs Lattice Matched to InP

1993 ◽  
Vol 324 ◽  
Author(s):  
V. Bellani ◽  
M. Amiotti ◽  
M. Geddo ◽  
G. Guizzetti ◽  
G. Landgren
Keyword(s):  
Energy Gap ◽  
Lattice Mismatch ◽  
Blue Shift ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Interfacial Strain ◽  
Valence Bands ◽  
Lattice Matched

AbstractWe measured photoreflectance (PR) spectra at different temperatures between 80 and 300 K, and optical absorption (OA) at 3 K on MOVPE grown Inl-xGaxAs nearly lattice-matched to InP. x-ray diffraction measurements gave a lattice mismatch δa/ao = -0.9.10−3 between ternary alloy and InP, corresponding to × = 0.485. We obtained the energy gap dependence on T from PR spectra. The blue shift of the gap was accounted for in terms of compositional difference with respect to the perfectly lattice matched alloy (× = 0.472), and elastic strain; moreover PR and OA showed evidence of the valence bands splitting at k = 0 due to interfacial strain, in fine agreement with theory.

scholarly journals Mechanical properties changes in fir wood (abies sp.), linden wood (tilia sp.), and beech wood (fagus sp.) subjected to various thermal modification process conditions

2021 ◽  
Vol 1208 (1) ◽  
pp. 012025
Author(s):  
Redžo Hasanagić ◽  
Sauradipta Ganguly ◽  
Ermin Bajramović ◽  
Adem Hasanagić
Keyword(s):  
Mechanical Properties ◽  
Beech Wood ◽  
Construction Materials ◽  
Treated Wood ◽  
Thermal Modification ◽  
Process Conditions ◽  
Modification Process ◽  
Maximum Duration ◽  
Different Temperatures ◽  
Control Samples

Abstract Wood is one of the most important construction materials in Europe and its use in building applications has increased in the recent decades. To enable even more extensive and reliable use of wood, this article aimed to determine the effect of thermal modification on mechanical properties of fir wood (lat. Abies sp.), linden wood (lat. Tilia sp.), and beech wood (lat. Fagus sp.). The thermal modification was conducted in a laboratory oven at five different temperatures of 170, 180, 195, 210, 220 °C and processed with a different maximum duration of the process of 78, 120, 180, 240, 276 minutes. Mechanical properties of treated wood have shown statistically insignificant fluctuations at lower temperatures compared to control samples. On the other hand, raising the temperature to 210 °C significantly affected the strength of all the species. The results revealed that thermal modification at high temperatures and longer exposure causes a decrease in the maximum force of the three wood species.

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