Substrate Induced Crystallinity in Reactive Sputter Deposition of Hydrogenated Silicon

1991 ◽  
Vol 219 ◽  
Author(s):  
G. F. Feng ◽  
M. Katiyar ◽  
J. R. Abelson ◽  
N. Maley
Keyword(s):  
Hydrogen Pressure ◽  
Crystalline Silicon ◽  
Native Oxide ◽  
Crystal Silicon ◽  
Hydrogenated Silicon ◽  
Reactive Sputter Deposition ◽  
Wide Range ◽  
Multi Wavelength ◽  
Fraction Increase

ABSTRACTWe use in situ multi-wavelength ellipsometry to study growth of hydrogenated amorphous silicon and crystalline silicon deposited by reactive DC magnetron sputtering. Crystal silicon covered with native oxide and oxide free crystal silicon are used as substrates. Deposition on c-Si/ox over a wide range of conditions yields amorphous films, and the growth proceeds with formation of small islands, regardless of hydrogen partial pressure. Growth on oxide free c-Si, on the other hand, is hydrogen dependent. Even at a low hydrogen pressure, a layer with mixed phase of c-Si and a-Si:H begin to appear near the c-Si substrate. This layer thickness and its c-Si fraction increase with hydrogen pressure. Bombardment of growing surface by energetic particles, both silicon and hydrogen species, appears to lead to the crystallization.

Heteroepitaxial Metal Oxides on Silicon by Laser Ablation

1990 ◽  
Vol 191 ◽  
Author(s):  
D. B. Fenner ◽  
D. K. Fork ◽  
G. A. N. Connell ◽  
J. B. Boyce ◽  
F. A. Ponce ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Single Crystal Silicon ◽  
Native Oxide ◽  
Silicon Substrates ◽  
X Ray Diffraction ◽  
Crystal Silicon ◽  
Ybco Films ◽  
Zero Resistance ◽  
High Degree

ABSTRACTThin epitaxial films of cubic - fluorite structured PrO2 and YSZ (yttria- stabilized zirconia) were grown on single crystal silicon substrates using the laser ablation - deposition technique. X-ray diffraction theta two - theta, omega rocking and phi scans indicate a high degree of epitaxial orientation of the films to the Si lattice. The highest quality of epitaxy was obtained with the PrO2 [111] oriented normal to Si(111) surfaces and the cubic YSZ [100] normal to Si(100) surfaces. For both PrO2 and YSZ, high epitaxial quality required the removal of the Si native oxide prior to deposition and careful control of the deposition environment. It was further found that the YSZ films on Si(100) were an excellent surface for subsequent laser ablation of YBCO films by the usual in situ process. The resistivity of this YBCO was ≈ 250 micro-ohm-cm at 300 K, extrapolated to the resistivity -temperature origin, showed a sharp transition to zero resistance at ≈ 85 K and was nearly identical to high quality YBCO films deposited on (bulk) YSZ substrates.

Thermally Driven In-Situ Removal of Native Oxide Using Anhydrous Hydrogen Fluoride

1993 ◽  
Vol 318 ◽  
Author(s):  
Pushkar P. Apte ◽  
Heungsoo Park ◽  
Krishna C. Saraswat ◽  
C. R. Helms
Keyword(s):  
Hydrogen Fluoride ◽  
Native Oxide ◽  
Epitaxial Silicon ◽  
Crystal Silicon ◽  
Silicon Deposition ◽  
Native Oxides ◽  
Anhydrous Hydrogen Fluoride ◽  
Thermally Driven ◽  
Oxide Removal

ABSTRACTIn-situ native-oxide removal is critical for epitaxial single-crystal silicon deposition, for polysilicon emitters and contacts and for ultrathin gate dielectric films in integrated circuit (IC) fabrication. We have developed an in-situ, thermally-driven, anhydrous hydrogen fluoride (AHF)-based native-oxide removal technique in which the wafer is treated by AHF at low temperatures (300-400°C) and a short (10 sec) 950°C ‘spike’ in AHF-H2 immediately prior to Si deposition. This process removes native oxides formed by standard wet cleans such as HC1:H202 and NH4OH:H202, as well as native oxides formed by the clean-room ambient. Further, the technique is an effective pre-clean for both polysilicon and epitaxial silicon deposition. This flexibility, combined with other salient features such as simplicity and a low thermal budget, make the process eminently suited for IC fabrication.

Real-time spectroscopic ellipsometry as an in-situ probe of the growth dynamics of amorphous and epitaxial crystal silicon for photovoltaic applications

2005 ◽  
Vol 862 ◽  
Author(s):  
D.H. Levi ◽  
C.W. Teplin ◽  
E. Iwaniczko ◽  
Y. Yan ◽  
T.H. Wang ◽  
...  
Keyword(s):  
Real Time ◽  
Spectroscopic Ellipsometry ◽  
Crystalline Silicon ◽  
Degree Of Crystallinity ◽  
Analysis Tool ◽  
Crystal Silicon ◽  
Tem Analysis ◽  
Photovoltaic Applications ◽  
Si Wafer

AbstractIn this paper we report on our work using in-situ real time spectroscopic ellipsometry (RTSE) to study the dynamics of hot-wire chemical vapor deposition (HWCVD) of hydrogenated amorphous silicon (a-Si:H) and epitaxial crystal silicon (epi-Si) for photovoltaic applications. We utilize RTSE as both an in-situ diagnostic and a postgrowth analysis tool for a-Si:H/crystalline silicon heterojunction (SHJ) solar cells and epi-silicon films grown by HWCVD. RTSE enables precise thickness control of the 3 to 10 nm thick layers used in the SHJ devices, as well as monitoring crystallinity and surface roughness in real time. With the assistance of in-situ RTSE feedback we have achieved a photovoltaic energy conversion efficiency of 17% on an Al-backed p-type float-zone c-Si wafer. Open-circuit voltages above 650 mV indicate excellent passivation of the c-Si surface by the a-Si:H intrinsic layer. We have used RTSE to obtain information on the degree of crystallinity and the electronic and optical properties of films as a function of deposition conditions. RTSE has indirectly indicated the persistence of a hydrogen layer at the interface between the a-Si:H layer and the crystal silicon substrate. Absorption spectra determined by RTSE have provided guidance in device optimization.We are also applying in-situ RTSE to study the dynamics of HWCVD growth of epi-Si. The goal of this work is to develop low-temperature methods for growing 2-10 μmthick layers of c-Si on c-Si seed layers on glass for solar cell applications. This study presents unique challenges for RTSE, as perfect epitaxial growth of c-Si on a c-Si wafer would produce no change at all in the RTSE spectra. We have found that by monitoring the pseudo-dielectric function in real time during growth we gain immediate feedback on the breakdown of epi-Si growth. Post-deposition analysis of the RTSE data provides quantitative information on the percent of c-Si and a-Si versus film thickness. The RTSE analysis has been confirmed by cross sectional TEM. Based on the rapid feedback provided by RTSE we have surpassed the previous HWCVD maxiumum of 200 nm of epi-Si growth, achieving a maximum thickness of 500 nm of epi-Si. TEM analysis has shown that micron-sized areas of these films achieve 1000 nm of epi-Si thickness.

Surface Microchemical Reactions during Hydrogenated Silicon Growth Studied by In-situ ESR Technique

2000 ◽  
Vol 609 ◽  
Author(s):  
Satoshi Yamasaki
Keyword(s):  
Crystalline Silicon ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Ultra High Vacuum ◽  
Dynamic Surface ◽  
Hydrogenated Silicon ◽  
Silicon Growth ◽  
Hydrogenated Amorphous

ABSTRACTThe in-situ ESR technique is applied to a plasma-enhanced chemical vapor deposition (PECVD) system in order to investigate the surface microchemical reactions during the growth of hydrogenated amorphous silicon (a-Si:H) and plasma treatments of H2 and Ar gases on a- Si:H. The growth model of a-Si:H and the role of H atoms on a-Si:H films are discussed using the experimental results. The recent results on the dynamic surface reactions of crystalline silicon with oxygen molecules in an ultra-high-vacuum ESR system are introduced.

In-situ electrical-resistivity measurements in the high-voltage electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 68-69
Author(s):  
W. E. King
Keyword(s):  
Electrical Resistivity ◽  
Electron Microscope ◽  
High Voltage ◽  
Resistivity Measurements ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Wide Range ◽  
Helium Gas

A side-entry type, helium-temperature specimen stage that has the capability of in-situ electrical-resistivity measurements has been designed and developed for use in the AEI-EM7 1200-kV electron microscope at Argonne National Laboratory. The electrical-resistivity measurements complement the high-voltage electron microscope (HVEM) to yield a unique opportunity to investigate defect production in metals by electron irradiation over a wide range of defect concentrations.A flow cryostat that uses helium gas as a coolant is employed to attain and maintain any specified temperature between 10 and 300 K. The helium gas coolant eliminates the vibrations that arise from boiling liquid helium and the temperature instabilities due to alternating heat-transfer mechanisms in the two-phase temperature regime (4.215 K). Figure 1 shows a schematic view of the liquid/gaseous helium transfer system. A liquid-gas mixture can be used for fast cooldown. The cold tip of the transfer tube is inserted coincident with the tilt axis of the specimen stage, and the end of the coolant flow tube is positioned without contact within the heat exchanger of the copper specimen block (Fig. 2).

Site specific agricultural soil management with the use of new technologies

2013 ◽  
Vol 16 (1) ◽  
pp. 59-67
Keyword(s):  
New Technologies ◽  
Digital Interface ◽  
Appropriate Treatment ◽  
Wide Range ◽  
Soil Variation ◽  
Soil Information ◽  
Remote Sensing Techniques ◽  
Agricultural Areas

<p>The Soil Science Institute of Thessaloniki produces new digitized Soil Maps that provide a useful electronic database for the spatial representation of the soil variation within a region, based on in situ soil sampling, laboratory analyses, GIS techniques and plant nutrition mathematical models, coupled with the local land cadastre. The novelty of these studies is that local agronomists have immediate access to a wide range of soil information by clicking on a field parcel shown in this digital interface and, therefore, can suggest an appropriate treatment (e.g. liming, manure incorporation, desalination, application of proper type and quantity of fertilizer) depending on the field conditions and cultivated crops. A specific case study is presented in the current work with regards to the construction of the digitized Soil Map of the regional unit of Kastoria. The potential of this map can easily be realized by the fact that the mapping of the physicochemical properties of the soils in this region provided delineation zones for differential fertilization management. An experiment was also conducted using remote sensing techniques for the enhancement of the fertilization advisory software database, which is a component of the digitized map, and the optimization of nitrogen management in agricultural areas.</p>

Indium Bromide-catalyzed Unprecedented Hydrogenolysis: A Novel One-Pot Synthesis of Per-O-Acetylated β-carboxymethyl O and S-glycosides

2020 ◽  
Vol 24 (8) ◽  
pp. 900-908
Author(s):  
Ram Naresh Yadav ◽  
Amrendra K Singh ◽  
Bimal Banik
Keyword(s):  
Asymmetric Synthesis ◽  
Chiral Auxiliary ◽  
Bioactive Molecules ◽  
One Pot ◽  
Enantiomerically Pure ◽  
Stereoselective Glycosylation ◽  
One Pot Synthesis ◽  
Wide Range

Numerous O (oxa)- and S (thia)-glycosyl esters and their analogous glycosyl acids have been accomplished through stereoselective glycosylation of various peracetylated bromo sugar with benzyl glycolate using InBr3 as a glycosyl promotor followed by in situ hydrogenolysis of resulting glycosyl ester. A tandem glycosylating and hydrogenolytic activity of InBr3 has been successfully investigated in a one-pot procedure. The resulting synthetically valuable and virtually unexplored class of β-CMGL (glycosyl acids) could serve as an excellent potential chiral auxiliary in the asymmetric synthesis of a wide range of enantiomerically pure medicinally prevalent β-lactams and other bioactive molecules of diverse medicinal interest.

scholarly journals A Generalization Performance Study Using Deep Learning Networks in Embedded Systems

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1031
Author(s):  
Joseba Gorospe ◽  
Rubén Mulero ◽  
Olatz Arbelaitz ◽  
Javier Muguerza ◽  
Miguel Ángel Antón
Keyword(s):  
Deep Learning ◽  
Embedded Systems ◽  
Embedded System ◽  
General Purpose ◽  
Learning Networks ◽  
Performance Study ◽  
Learning Techniques ◽  
Wide Range ◽  
Learning Architectures

Deep learning techniques are being increasingly used in the scientific community as a consequence of the high computational capacity of current systems and the increase in the amount of data available as a result of the digitalisation of society in general and the industrial world in particular. In addition, the immersion of the field of edge computing, which focuses on integrating artificial intelligence as close as possible to the client, makes it possible to implement systems that act in real time without the need to transfer all of the data to centralised servers. The combination of these two concepts can lead to systems with the capacity to make correct decisions and act based on them immediately and in situ. Despite this, the low capacity of embedded systems greatly hinders this integration, so the possibility of being able to integrate them into a wide range of micro-controllers can be a great advantage. This paper contributes with the generation of an environment based on Mbed OS and TensorFlow Lite to be embedded in any general purpose embedded system, allowing the introduction of deep learning architectures. The experiments herein prove that the proposed system is competitive if compared to other commercial systems.

scholarly journals Global soil moisture data derived through machine learning trained with in-situ measurements

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Sungmin O. ◽  
Rene Orth
Keyword(s):  
Machine Learning ◽  
Soil Moisture ◽  
Large Scale ◽  
Short Term Memory ◽  
Temporal Dynamics ◽  
Soil Moisture Data ◽  
Wide Range ◽  
Global Soil

AbstractWhile soil moisture information is essential for a wide range of hydrologic and climate applications, spatially-continuous soil moisture data is only available from satellite observations or model simulations. Here we present a global, long-term dataset of soil moisture derived through machine learning trained with in-situ measurements, SoMo.ml. We train a Long Short-Term Memory (LSTM) model to extrapolate daily soil moisture dynamics in space and in time, based on in-situ data collected from more than 1,000 stations across the globe. SoMo.ml provides multi-layer soil moisture data (0–10 cm, 10–30 cm, and 30–50 cm) at 0.25° spatial and daily temporal resolution over the period 2000–2019. The performance of the resulting dataset is evaluated through cross validation and inter-comparison with existing soil moisture datasets. SoMo.ml performs especially well in terms of temporal dynamics, making it particularly useful for applications requiring time-varying soil moisture, such as anomaly detection and memory analyses. SoMo.ml complements the existing suite of modelled and satellite-based datasets given its distinct derivation, to support large-scale hydrological, meteorological, and ecological analyses.

scholarly journals Quantification of assembly forces during creation of head-neck taper junction considering soft tissue bearing: a biomechanical study

Arthroplasty ◽  
2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Toni Wendler ◽  
Torsten Prietzel ◽  
Robert Möbius ◽  
Jean-Pierre Fischer ◽  
Andreas Roth ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Work Experience ◽  
Soft Tissues ◽  
Force Sensor ◽  
Biomechanical Study ◽  
Measuring System ◽  
Wide Range ◽  
Head Neck

Abstract Background All current total hip arthroplasty (THA) systems are modular in design. Only during the operation femoral head and stem get connected by a Morse taper junction. The junction is realized by hammer blows from the surgeon. Decisive for the junction strength is the maximum force acting once in the direction of the neck axis, which is mainly influenced by the applied impulse and surrounding soft tissues. This leads to large differences in assembly forces between the surgeries. This study aimed to quantify the assembly forces of different surgeons under influence of surrounding soft tissue. Methods First, a measuring system, consisting of a prosthesis and a hammer, was developed. Both components are equipped with a piezoelectric force sensor. Initially, in situ experiments on human cadavers were carried out using this system in order to determine the actual assembly forces and to characterize the influence of human soft tissues. Afterwards, an in vitro model in the form of an artificial femur (Sawbones Europe AB, Malmo, Sweden) with implanted measuring stem embedded in gelatine was developed. The gelatine mixture was chosen in such a way that assembly forces applied to the model corresponded to those in situ. A study involving 31 surgeons was carried out on the aforementioned in vitro model, in which the assembly forces were determined. Results A model was developed, with the influence of human soft tissues being taken into account. The assembly forces measured on the in vitro model were, on average, 2037.2 N ± 724.9 N, ranging from 822.5 N to 3835.2 N. The comparison among the surgeons showed no significant differences in sex (P = 0.09), work experience (P = 0.71) and number of THAs performed per year (P = 0.69). Conclusions All measured assembly forces were below 4 kN, which is recommended in the literature. This could lead to increased corrosion following fretting in the head-neck interface. In addition, there was a very wide range of assembly forces among the surgeons, although other influencing factors such as different implant sizes or materials were not taken into account. To ensure optimal assembly force, the impaction should be standardized, e.g., by using an appropriate surgical instrument.

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