Si Surface Preparation with Si Beam Irradiation on the Growth of III-V on Si

1997 ◽  
Vol 485 ◽  
Author(s):  
H. Kawanami ◽  
K. Baskar ◽  
I. Sakata ◽  
T. Sekigawa
Keyword(s):  
Substrate Temperature ◽  
Substrate Surface ◽  
Surface Preparation ◽  
Photoluminescence Spectra ◽  
Slight Improvement ◽  
Beam Irradiation ◽  
Irradiation Effects ◽  
Experimental Conditions ◽  
Initial Substrate

AbstractThe preliminary results of the effects of the Si beam irradiation for the Si surface preparation on the growth of GaAs on Si by MBE are reported. The effects are combined with thermal cyclic anneal (TCA). A slight improvement in the crystalline quality is observed on the photoluminescence spectra of the films grown with Si irradiation. In our experimental conditions, Si irradiation during the Si surface preparation has not indicated large effects on the FWHM of XRD. It is also indicated that initial substrate surface treatment affects the quality of thicker film through TCA treatment. Higher substrate temperature during Si beam irradiation is expected to indicate positive Si beam irradiation effects.

On-Line Control of Particle Spray Jet and Residual Stresses in Plasma Sprays

2000 ◽  
Author(s):  
T. Renault ◽  
M. Vardelle ◽  
A. Grimaud ◽  
P. Fauchais ◽  
H. Hoffman
Keyword(s):  
Residual Stresses ◽  
Substrate Temperature ◽  
Particle Velocity ◽  
Low Cost ◽  
Substrate Surface ◽  
Surface Preparation ◽  
Ccd Camera ◽  
Powder Injection ◽  
Input Parameters ◽  
On Line

Abstract The quality of plasma sprayed coatings depends strongly on substrate surface preparation, especially roughness, grit residue, and oxidation stage; particle spray jet position and size relative to the plasma jet; impacting particle distribution; particle velocity, temperature, and size prior to impact; substrate temperature; and pass thickness. A simple and low-cost spray and deposit control system developed in our laboratory allows to monitor on-line the position, shape, and centroid of the hot particle spray jet. Such a tool has proved to be very sensitive to any drift in powder injection conditions and torch input parameters. Although it gives no direct information on particle velocity and temperature, this system can be easily implemented in an industrial environment and help to maintain constant the particle parameters during spraying. A CCD camera is used in conjunction with a pyrometer making it possible to measure simultaneously substrate temperature. The system can monitor coating parameters such as deposition efficiency and residual stresses. This paper describes how the system can be used to set the tolerance range of process input parameters to obtain coating parameters within given specifications.

EFFECTS OF SUBSTRATE AND EXPERIMENTAL CONDITIONS ON THE FABRICATION OF WELL-ORDERED SILICA PARTICULATE LANGMUIR–BLODGETT FILMS

2013 ◽  
Vol 20 (03n04) ◽  
pp. 1350039 ◽  
Author(s):  
YUDI GUO ◽  
DONGYAN TANG ◽  
SHUO GU
Keyword(s):  
Substrate Surface ◽  
Chemical Bonds ◽  
Sem Images ◽  
Experimental Conditions ◽  
Oh Groups ◽  
Langmuir Blodgett ◽  
Withdrawal Speed ◽  
Langmuir Blodgett Films ◽  
Surface Nature

The dependence of particulate Langmuir–Blodgett (LB) monolayer quality on the surface nature of the substrate was investigated by pretreating the substrates with different methods, and the optimal withdrawal speed was determined by detecting the quality of particulate monolayers deposited at different withdrawal speeds. Furthermore, the effects of stearic acid (SA) concentration on the quality of particulate monolayers were discussed. Results indicated that surface amination would favor the transfer of the floating particulate monolayer from the interface to the substrate, which would be attributed to the formation of chemical bonds between the – NH 2 groups on the substrate surface and the functional groups of – COOH and Si – OH groups on surfaces of particles floating at the interface. And the withdrawal speed of 1 mm ⋅ min-1 was appropriate for the fabrication of high-quality particulate LB monolayer because low withdrawal speed can offer sufficient time to form chemical bonds and expel the subphase from the substrate. Additionally, SEM images illustrated that the SA concentration of 0.40 mg ⋅ mL-1 was suitable for the fabrication of well-ordered particulate LB monolayers composed by the particles of 380 nm.

Growth and Structure of Germanium Films Evaporated Onto Rock Salt

1970 ◽  
Vol 28 ◽  
pp. 512-513
Author(s):  
G. Shimaoka ◽  
S. C. Chang
Keyword(s):  
Thin Films ◽  
Electron Beam ◽  
Substrate Temperature ◽  
Rock Salt ◽  
Electron Beam Irradiation ◽  
Substrate Surface ◽  
Beam Irradiation ◽  
Deposition Rates ◽  
Surface Conditions ◽  
Germanium Films

Recent studies of evaporated germanium films have demonstrated that their structure and epitaxy are greatly influenced by various evaporation parameters such as vacuum pressure, substrate surface conditions, and deposition rate as veil as substrate temperature. The purpose of this study is to investigate growth and structure of germanium thin films evaporated onto a clean rock-salt substrate in ultrahlgh vacuum and to find optimum epitaxial growth condition.High-purity (intrinsic) germanium was evaporated at various deposition rates, 0.1-5Å/sec, and thicknesses, 3O-5OOÅ, onto vacuum-cleaved and air-cleaved (001)NaCl substrates held at 25°-500°C in a vacuum of ∼10-8Torr. Some films were prepared under lateral electric field of dc 100V/cm or an electron-beam irradiation with ∼1015 electrons/cm2/sec, 300-400V, applied to the substrate during evaporation.

Numerical Study on Rapid Solidification of a Plasma-Sprayed Cast Iron Splat on a High-Temperature Substrate

2009 ◽  
Vol 79-82 ◽  
pp. 1129-1132 ◽  
Author(s):  
Ya Zhe Xing ◽  
Qiu Lan Wei ◽  
Jian Min Hao ◽  
Can Shang
Keyword(s):  
Cast Iron ◽  
Substrate Temperature ◽  
Rapid Solidification ◽  
Numerical Study ◽  
Substrate Surface ◽  
Melt Temperature ◽  
Metallurgical Bonding ◽  
Initial Substrate ◽  
Plasma Sprayed ◽  
Iron Coatings

In this work, an experiment was performed to demonstrate the possibility of the metallurgical bonding in plasma-sprayed cast iron coatings at high substrate temperature. A quantitative analysis of splat cooling and rapid solidification of cast iron splat is then presented. The effect of the substrate temperature on the development of melt undercooling within the splat is investigated in detail. The results indicated that the initial substrate temperature has a profound effect on the development of melt undercooling in a splat, the splat bottom melt temperature, and the substrate surface temperature. A high initial temperature of the substrate restrains the cooling of the splat and leads to a high melt temperature that may promote the grain growth directly on cast iron substrate surface to form the metallurgical bonding.

Structural Evaluation of Graphene/SiC (0001) Grown in Atmospheric Pressure

2010 ◽  
Vol 645-648 ◽  
pp. 573-576 ◽  
Author(s):  
John Boeckl ◽  
W.C. Mitchel ◽  
Edwina Clarke ◽  
Roland L. Barbosa ◽  
Wei Jie Lu
Keyword(s):  
Atmospheric Pressure ◽  
Substrate Surface ◽  
Surface Preparation ◽  
Graphene Growth ◽  
Disordered Structures ◽  
Structural Evaluation ◽  
Entire Substrate Surface ◽  
Atomically Flat

Graphene growth on SiC in atmospheric pressure argon exhibits large terrace sizes and coverage over the entire substrate surface. Graphene growth and the resulting morphology are correlated with the characteristics of the growth chamber and the surface quality of the starting SiC substrate. Without in-situ surface preparation prior to growth, we observe “wrinkles” in the graphene surface. Graphitic-like disordered structures are formed at 1500°C while atomically flat graphene terraces are formed above 1600°C.

Thin Metal Film Adhesion Studies on GaAs

1986 ◽  
Vol 77 ◽  
Author(s):  
T. T. Bardin ◽  
J. G. Pronko ◽  
D. K. Kinell
Keyword(s):  
Ion Beam ◽  
Substrate Surface ◽  
Surface Preparation ◽  
Thin Metal Film ◽  
Optimum Conditions ◽  
Adhesive Properties ◽  
Ion Beam Mixing ◽  
Film Adhesion ◽  
Thin Film Adhesion

ABSTRACTComparative thin film adhesion studies were performed on GaAs substrates using Au or Au-Ni-Ge, metallization materials. The influence of parameters such as crystal orientation, substrate surface preparation, deposition vacuum conditions, thickness and composition of films, and post-evaporative treatment such as ion-beam mixing and thermal annealing, on film adhesion was considered. The quality of the adhesion bond was measured using Scotch tape tests and a Sebastian adhesion tester. Film interfaces were characterized using AES, XPS, and RBS techniques. The results indicate that the most important factors dominating the quality of adhesion were surface preparation and the deposition vacuum conditions. Films deposited under optimum conditions were found to adhere so well that the GaAs crystal would fracture before the film would pull free of the substrate. The influence of ion beam mixing on the quality of adhesion was tested and only in the cases of depositions under the less optimum conditions, where the adhesion was poor, could an improvement be made in the adhesive properties.

Characterization of homoepitaxial diamond films by Electron microscopy

1991 ◽  
Vol 49 ◽  
pp. 880-881
Author(s):  
D.P. Malta ◽  
S.A. Willard ◽  
R.A. Rudder ◽  
G.C. Hudson ◽  
J.B. Posthill ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Surface Defects ◽  
Substrate Surface ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Large Degree ◽  
Rf Plasma ◽  
Semiconducting Diamond

Semiconducting diamond films have the potential for use as a material in which to build active electronic devices capable of operating at high temperatures or in high radiation environments. A major goal of current device-related diamond research is to achieve a high quality epitaxial film on an inexpensive, readily available, non-native substrate. One step in the process of achieving this goal is understanding the nucleation and growth processes of diamond films on diamond substrates. Electron microscopy has already proven invaluable for assessing polycrystalline diamond films grown on nonnative surfaces.The quality of the grown diamond film depends on several factors, one of which is the quality of the diamond substrate. Substrates commercially available today have often been found to have scratched surfaces resulting from the polishing process (Fig. 1a). Electron beam-induced current (EBIC) imaging shows that electrically active sub-surface defects can be present to a large degree (Fig. 1c). Growth of homoepitaxial diamond films by rf plasma-enhanced chemical vapor deposition (PECVD) has been found to planarize the scratched substrate surface (Fig. 1b).

Methods to Monitor and Improve the Performance of Specimen Holders for Transmission Electron Cryomicroscopy

1996 ◽  
Vol 54 ◽  
pp. 454-455
Author(s):  
B. L. Armbruster ◽  
B. Kraus ◽  
M. Pan
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Electron Beam Irradiation ◽  
Beam Irradiation ◽  
Quality Of Data ◽  
Electron Cryomicroscopy ◽  
Thermal Equilibration ◽  
Transmission Electron ◽  
Electron Microscopes

One goal in electron microscopy of biological specimens is to improve the quality of data to equal the resolution capabilities of modem transmission electron microscopes. Radiation damage and beam- induced movement caused by charging of the sample, low image contrast at high resolution, and sensitivity to external vibration and drift in side entry specimen holders limit the effective resolution one can achieve. Several methods have been developed to address these limitations: cryomethods are widely employed to preserve and stabilize specimens against some of the adverse effects of the vacuum and electron beam irradiation, spot-scan imaging reduces charging and associated beam-induced movement, and energy-filtered imaging removes the “fog” caused by inelastic scattering of electrons which is particularly pronounced in thick specimens.Although most cryoholders can easily achieve a 3.4Å resolution specification, information perpendicular to the goniometer axis may be degraded due to vibration. Absolute drift after mechanical and thermal equilibration as well as drift after movement of a holder may cause loss of resolution in any direction.

Improvement in Gate Dielectric Quality of Ultra Thin a: SiN:H MNS Capacitor by Hydrogen Etching of the Substrate

2002 ◽  
Vol 716 ◽  
Author(s):  
Parag C. Waghmare ◽  
Samadhan B. Patil ◽  
Rajiv O. Dusane ◽  
V.Ramgopal Rao
Keyword(s):  
Silicon Nitride ◽  
Gate Dielectric ◽  
Substrate Surface ◽  
Scaling Limit ◽  
Tunneling Current ◽  
Chemical Vapor ◽  
Poor Performance ◽  
State Density ◽  
Direct Tunneling Current

AbstractTo extend the scaling limit of thermal SiO2, in the ultra thin regime when the direct tunneling current becomes significant, members of our group embarked on a program to explore the potential of silicon nitride as an alternative gate dielectric. Silicon nitride can be deposited using several CVD methods and its properties significantly depend on the method of deposition. Although these CVD methods can give good physical properties, the electrical properties of devices made with CVD silicon nitride show very poor performance related to very poor interface, poor stability, presence of large quantity of bulk traps and high gate leakage current. We have employed the rather newly developed Hot Wire Chemical Vapor Deposition (HWCVD) technique to develop the a:SiN:H material. From the results of large number of optimization experiments we propose the atomic hydrogen of the substrate surface prior to deposition to improve the quality of gate dielectric. Our preliminary results of these efforts show a five times improvement in the fixed charges and interface state density.

A Critical Review of Morphologic Findings and Data From 14 Toxicological Studies Involving Fish Exposures to Diclofenac

2021 ◽  
pp. 019262332198965
Author(s):  
Jeffrey C. Wolf
Keyword(s):  
Diagnostic Errors ◽  
Data Interpretation ◽  
Included Study ◽  
Experimental Conditions ◽  
Regulatory Decision ◽  
Transmission Electron ◽  
Toxicological Studies ◽  
Morphologic Data ◽  
Ambiguous Data

A number of studies have investigated the potential toxicity of the analgesic agent diclofenac (DCF) in various fish species under a diverse array of experimental conditions. Reported evidence of toxicity in these investigations is often strongly reliant on morphologic end points such as histopathology, immunohistochemistry, and transmission electron microscopy. However, it may be challenging for scientists who perform environmental hazard or risk determination to fully appreciate the intricacies of these specialized endpoints. Therefore, the purpose of the current review was to critically assess the quality of morphologic data in 14 papers that described the experimental exposure of fish to DCF. Areas of focus during this review included study design, diagnostic accuracy, magnitude of reported changes, data interpretation and presentation, and the credibility of individual reported findings. Positive attributes of some studies included robust experimental designs, accurate diagnoses, and straightforward and transparent data reporting. Issues identified in certain articles included diagnostic errors, failure to account for sampling and/or observer bias, failure to evaluate findings according to sex, exaggeration of lesion severity, interstudy inconsistencies, unexplained phenomena, and incomplete or ambiguous data presentation. It is hoped that the outcome of this review will be of value for personnel involved in regulatory decision-making.

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