scholarly journals Improvement the InAs, InSb, GaAs and GaSb surface state by nanoscale wet etching

2021 ◽  
Author(s):  
Iryna Levchenko ◽  
Vasyl Tomashyk ◽  
Galyna Malanych ◽  
Iryna Stratiychuk ◽  
Andrii Korchovyi
Keyword(s):  
Surface State ◽  
Smooth Surface ◽  
Crystal Surface ◽  
Wet Etching ◽  
Solvent Concentration ◽  
Solution Composition ◽  
Crystal Dissolution ◽  
Semiconductor Etching ◽  
Experimental Approaches ◽  
Nanoscale Roughness

AbstractVarious experimental approaches of the wet nanoscale treatment have been proposed to account for features of the InAs, InSb and GaAs, GaSb semiconductor dissolution process in the (NH4)2Cr2O7–HBr–EG etching solution. Etching kinetics data showed that a crystal dissolution has diffusion-determined nature. The lowering of the solvent concentration from 80 to 0 vol.% in the solution was accompanied by a significant increase in the semiconductor etching speed. Depending on the solution composition, we have studied two types of crystal surface morphology, polished and passivated by the film, which was formed after chemical-dynamic (CDP) and/or chemical-mechanic polishing (CMP) in the solution, saturated by solvent and by oxidant, accordingly. It was found that in the polished etchants both CDP and CMP procedures lead to the formation of the mirror-like and super-smooth surface with nanoscale roughness less than 1 nm. The obtained results of surface state indicate that the (NH4)2Cr2O7–HBr–EG etchants could be used successfully for controllable CDP and CMP treatment of III–V semiconductors and formation of super-smooth surface.

Optimal Design of an Electrothermal Microfluidic Pump

2009 ◽  
Author(s):  
E. Du ◽  
Souran Manoochehri
Keyword(s):  
Flow Pattern ◽  
Flow Rate ◽  
Smooth Surface ◽  
Wet Etching ◽  
Oscillating Flow ◽  
Planar Case ◽  
Ac Electrokinetics ◽  
Actuation Mechanism ◽  
Pumping System ◽  
Optimization Methodology

AC electrokinetics in microfluidic systems has been extensively investigated for its great potential in microfluidic pumping applications. The oscillating flow pattern in a microchannel with planar floor configuration restricts the pumping capacity due to the fast recirculating vortices over the electrode surface positioned in the microchannel floor. Patterned microgrooved floor in a fluidic microchannel can be employed to modify the flow pattern and make it uniaxial thus increase the net flow rate. Silicon KOH wet etching can be utilized to fabricate the microgrooved floor of the channel for its highly smooth surface quality and precise and reproducible configuration. We have developed an optimization methodology for the design of microgrooved configuration for a microfluidic pump using alternating current electrothermal (AC ET) actuation mechanism. The flow rate for the AC ET pumping system with optimized microgrooved floor can be higher as compared to the planar case without any significant increases of the temperature profile. In this paper, we are presenting the results of an optimum microgrooved floor configuration for an effective pumping application.

Intracrystalline urinary proteins facilitate degradation and dissolution of calcium oxalate crystals in cultured renal cells

2008 ◽  
Vol 294 (2) ◽  
pp. F355-F361 ◽  
Author(s):  
Phulwinder K. Grover ◽  
Lauren A. Thurgood ◽  
David E. Fleming ◽  
Wilhelm van Bronswijk ◽  
Tingting Wang ◽  
...  
Keyword(s):  
Calcium Oxalate ◽  
Crystallite Size ◽  
Surface Area ◽  
Crystal Surface ◽  
Scanning Electron Micrographs ◽  
Radioactive Label ◽  
Crystal Dissolution ◽  
Mdckii Cells ◽  
Nonuniform Strain ◽  
Scanning Electron

We have previously proposed that intracrystalline proteins would increase intracellular proteolytic disruption and dissolution of calcium oxalate (CaOx) crystals. Chauvet MC, Ryall RL. J Struct Biol 151: 12–17, 2005; Fleming DE, van Riessen A, Chauvet MC, Grover PK, Hunter B, van Bronswijk W, Ryall RL. J Bone Miner Res 18: 1282–1291, 2003; Ryall RL, Fleming DE, Doyle IR, Evans NA, Dean CJ, Marshall VR. J Struct Biol 134: 5–14, 2001. The aim of this investigation was to determine the effect of increasing concentrations of intracrystalline protein on the rate of CaOx crystal dissolution in Madin-Darby canine kidney (MDCKII) cells. Crystal matrix extract (CME) was isolated from urinary CaOx monohydrate (COM) crystals. Cold and [14C]oxalate-labeled COM crystals were precipitated from ultrafiltered urine containing 0–5 mg/l CME. Crystal surface area was estimated from scanning electron micrographs, and synchrotron X-ray diffraction was used to determine nonuniform strain and crystallite size. Radiolabeled crystals were added to MDCKII cells and crystal dissolution, expressed as radioactive label released into the medium, was measured. Increasing CME content did not significantly alter crystal surface area. However, nonuniform strain increased and crystallite size decreased in a dose-response manner, both reaching saturation at a CME concentration of 3 mg/ and demonstrating unequivocally the inclusion of increasing quantities of proteins in the crystals. This was confirmed by Western blotting. Crystal dissolution also followed saturation kinetics, increasing proportionally with final CME concentration and reaching a plateau at a concentration of ∼2 mg/l. These findings were complemented by field emission scanning electron microscopy, which showed that crystal degradation also increased relative to CME concentration. Intracrystalline proteins enhance degradation and dissolution of CaOx crystals and thus may constitute a natural defense against urolithiasis. The findings have significant ramifications in biomineral metabolism and pathogenesis of renal stones.

PHOTOLUMINESCENCE ENHANCEMENT AND THERMAL PERFORMANCE OF SURFACE MODIFIED Y3Al5O12:Ce3+ PHOSPHOR BY CHEMICAL WET ETCHING

2013 ◽  
Vol 06 (01) ◽  
pp. 1350008 ◽  
Author(s):  
ZHIJIANG HE ◽  
ZEBIN LI ◽  
XIAOXUAN FAN ◽  
WEIHAI CHENG ◽  
JIAQI JU ◽  
...  
Keyword(s):  
Surface Modification ◽  
Decay Rate ◽  
Thermal Performance ◽  
Smooth Surface ◽  
Wet Etching ◽  
Emission Power ◽  
Temperature Decay ◽  
Photoluminescence Enhancement ◽  
Lower Temperature ◽  
Surface Modified

Surface of Y3Al5O12 : Ce3+ Phosphor was modified by wet etching in 40% NH4F+CH3COOH (1:1) solution for 5 h. SEM results show that smooth surface of phosphor particles turn rough, and edge angles are less sharp as before. PL determinations indicate that backscattering loss of the excited light reduces by 3.9% and emission power is enhanced by 10.7%. Meanwhile, after the surface modification, YAG phosphor presents a lower temperature decay rate of 1.2% at 373 K, which is well explained by the configurational coordinate diagram. Therefore, this method can greatly enhance the efficient of light conversion, extraction and stabilization of pc-LED.

scholarly journals Estimating the activation energy of bond hydrolysis by time-resolved weighing of dissolving crystals

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Philippe Ackerer ◽  
Arnaud Bouissonnié ◽  
Raphael di Chiara Roupert ◽  
Damien Daval
Keyword(s):  
Activation Energy ◽  
Crystal Surface ◽  
Calibration Method ◽  
Solute Concentration ◽  
Bond Breaking ◽  
Dissolution Rates ◽  
Experimental Conditions ◽  
Time Resolved ◽  
Crystal Dissolution ◽  
Dissolution Model

AbstractBond-breaking activation energy EB is nowadays a key parameter for understanding and modeling crystal dissolution processes. However, a methodology to estimate EB based on classical dissolution experiments still does not exist. We developed a new method based on the calibration of a Kossel type dissolution model on measured dissolution rates obtained by mass (or volume) variations over time. The dissolution model does not depend on the geometry of the crystal surface but only on the density of the different types of sites (kink, step, terrace, bulk). The calibration method was applied to different experimental setups (flow through and batch) with different ways of estimating the dissolution rates (solute concentration in the fluid, surface topography) for calcite crystals. Despite the variety of experimental conditions, the estimated bond-breaking activation energies were very close to each other (between 31 and 35 kJ/mol) and in good agreement with ab initio calculations.

Researches concerning the Aerodynamic Sorting of Solid Particles According to the Surface States

2008 ◽  
Vol 59 (3) ◽  
pp. 360-365 ◽  
Author(s):  
Valentin Nedeff ◽  
Emilian Mosnegutu ◽  
Mirela Panainte ◽  
Carment Savin ◽  
Bogdan Macarescu
Keyword(s):  
Binary Mixture ◽  
Rough Surface ◽  
Surface State ◽  
Smooth Surface ◽  
Surface Condition ◽  
Surface States ◽  
Aerodynamic Characteristics ◽  
Solid Particles ◽  
Separation Degree ◽  
Sorting Process

The process of aerodynamic sorting of a solid particles mixture is influenced by the aerodynamic characteristics of the particles (shape, dimensions, the surface state and the density of the particle), which determine the behaviour of particles in the air flows. In this study it was analyzed the influence of the surface state of solid particles on the separation degree of a binary mixture, made from particles with smooth surface and particles with rough surface, submitted to the aerodynamic sorting. The correlation between the surface state of solid particles and their behavior in air flow is emphasized by the weight mass of the particles deposited in the collection boxes. It was observed that the particles with the smooth surface have higher floating velocities than the particles with the rough surface for closed dimensions, shapes and densities. The sorting process is influenced by the surface condition of the particle.

scholarly journals Surfactant-Free Synthesis of Reduced Graphene Oxide Supported Well-Defined Polyhedral Pd-Pt Nanocrystals for Oxygen Reduction Reaction

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 756 ◽  
Author(s):  
Yongfu Tang ◽  
Teng Chen ◽  
Wenfeng Guo
Keyword(s):  
Graphene Oxide ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Reduced Graphene Oxide ◽  
Surface State ◽  
Smooth Surface ◽  
Reduction Reaction ◽  
Methanol Tolerance ◽  
Reduced Graphene ◽  
Pt Nanocrystals

Well-defined polyhedral Pd-Pt nanocrystals anchored on the reduced graphene oxide (rGO) are successfully synthesized via a facile and efficient surfactant-free solvothermal route. The formation mechanism is carefully illustrated via tuning the surface state of rGO substrate and the Pd/Pt ratio in Pd-Pt nanocrystals. rGO substrates with continuous smooth surface, which can offer continuous 2D larger π electrons, play important roles in the formation of the well-defined polyhedral Pd-Pt nanocrystals. Suitable Pd/Pt ratio, which determines the affinity between the rGO substrate and polyhedral Pd-Pt nanocrystals, is another important factor for the formation of polyhedral Pd-Pt nanocrystals. Due to the well-defined surface of Pd-Pt nanocrystals, rich corners and edges from polyhedral structure, as well as more exposed (111) facets, the low-Pt polyhedral Pd-Pt nanocrystals anchored on rGO, used as electrocatalysts, exhibit high electrocatalytic activity for oxygen reduction reaction with excellent methanol tolerance.

Convergent Beam Electron Diffraction

1978 ◽  
Vol 36 (3) ◽  
pp. 304-315
Author(s):  
G. Lehmpfuhl
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Crystal Surface ◽  
Diffraction Spot ◽  
Crystal Thickness ◽  
Large Area ◽  
Electron Microscopic ◽  
Additional Information ◽  
Microscopic Investigations

Introduction In electron microscopic investigations of crystalline specimens the direct observation of the electron diffraction pattern gives additional information about the specimen. The quality of this information depends on the quality of the crystals or the crystal area contributing to the diffraction pattern. By selected area diffraction in a conventional electron microscope, specimen areas as small as 1 µ in diameter can be investigated. It is well known that crystal areas of that size which must be thin enough (in the order of 1000 Å) for electron microscopic investigations are normally somewhat distorted by bending, or they are not homogeneous. Furthermore, the crystal surface is not well defined over such a large area. These are facts which cause reduction of information in the diffraction pattern. The intensity of a diffraction spot, for example, depends on the crystal thickness. If the thickness is not uniform over the investigated area, one observes an averaged intensity, so that the intensity distribution in the diffraction pattern cannot be used for an analysis unless additional information is available.

Crystal Structure Determination of Glycerol-Containing Lipids from Electron Diffraction Data. Use of Analog Compounds Based upon Configurational Isomers of Cyclopentane-1, 2, 3-TRIOL

1977 ◽  
Vol 35 ◽  
pp. 24-25
Author(s):  
Douglas L. Dorset ◽  
Anthony J. Hancock
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Crystal Surface ◽  
Coherent Scattering ◽  
Crystal Structure Determination ◽  
Electron Diffraction Data ◽  
Polar Group ◽  
Axis Orientation

Lipids containing long polymethylene chains were among the first compounds subjected to electron diffraction structure analysis. It was only recently realized, however, that various distortions of thin lipid microcrystal plates, e.g. bends, polar group and methyl end plane disorders, etc. (1-3), restrict coherent scattering to the methylene subcell alone, particularly if undistorted molecular layers have well-defined end planes. Thus, ab initio crystal structure determination on a given single uncharacterized natural lipid using electron diffraction data can only hope to identify the subcell packing and the chain axis orientation with respect to the crystal surface. In lipids based on glycerol, for example, conformations of long chains and polar groups about the C-C bonds of this moiety still would remain unknown.One possible means of surmounting this difficulty is to investigate structural analogs of the material of interest in conjunction with the natural compound itself. Suitable analogs to the glycerol lipids are compounds based on the three configurational isomers of cyclopentane-1,2,3-triol shown in Fig. 1, in which three rotameric forms of the natural glycerol derivatives are fixed by the ring structure (4-7).

Studies of Oxide Formation on Copper Thin Films by Electron Microscopy

1977 ◽  
Vol 35 ◽  
pp. 316-317
Author(s):  
G. G. Hembree ◽  
M. A. Otooni ◽  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
Single Crystal ◽  
Crystal Surface ◽  
Crystal Defects ◽  
Diffraction Reflection ◽  
Reaction Products ◽  
Intermediate Energies ◽  
Crystal Films ◽  
Reflection Electron Microscopy

The formation of oxide structures on single crystal films of metals has been investigated using the REMEDIE system (for Reflection Electron Microscopy and Electron Diffraction at Intermediate Energies) (1). Using this instrument scanning images can be obtained with a 5 to 15keV incident electron beam by collecting either secondary or diffracted electrons from the crystal surface (2). It is particularly suited to studies of the present sort where the surface reactions are strongly related to surface morphology and crystal defects and the growth of reaction products is inhomogeneous and not adequately described in terms of a single parameter. Observation of the samples has also been made by reflection electron diffraction, reflection electron microscopy and replication techniques in a JEM-100B electron microscope.A thin single crystal film of copper, epitaxially grown on NaCl of (100) orientation, was repositioned on a large copper single crystal of (111) orientation.

Sign in / Sign up

Export Citation Format

Share Document