scholarly journals Wet Chemical Etching of AlN Single Crystals

2002 ◽  
Vol 7 ◽  
Author(s):  
D. Zhuang ◽  
J.H. Edgar ◽  
Lianghong Liu ◽  
B. Liu ◽  
L. Walker
Keyword(s):  
Single Crystals ◽  
Basal Plane ◽  
Chemical Etching ◽  
Potassium Hydroxide ◽  
Defect Density ◽  
Potassium Hydroxide Solution ◽  
Aqueous Potassium Hydroxide ◽  
Important Means ◽  
Wet Chemical ◽  
Image Position

Anisotropic chemical etching is an important means for characterizing the polarity and defect density of single crystals. In this letter, we present the results of our studies on the etching of bulk AlN crystals in aqueous potassium hydroxide solution. The nitrogen polarity (0001) basal plane initially etched rapidly, while the aluminum polarity basal plane, and prismatic (100) planes were not etched. The etch rate of the nitrogen polarity basal plane eventually decreased to zero, as the surface became completely covered with hexagonal hillocks which were bounded by {101} planes. The hillock density for the self-seeded AlN crystals studied was typically in the range of 5×107cm−2 to 109cm−2. From our analysis of etched AlN crystals, we infer that freely nucleated crystals predominately have the nitrogen to aluminum direction pointing out from the nucleation surface, that is the ends of the AlN crystals facing the source are aluminum polarity.

Reactions of tert-Butyl Peroxy Esters, XIV. Further Observations on the Preparation of Dialkyl tert-Butylperoxy Phosphates

1975 ◽  
Vol 30 (9-10) ◽  
pp. 732-739 ◽  
Author(s):  
G. Sosnovsky ◽  
E. H. Zaret
Keyword(s):  
Potassium Hydroxide ◽  
Potassium Hydroxide Solution ◽  
Sodium Hydride ◽  
High Yield ◽  
Butyl Hydroperoxide ◽  
Tert Butyl ◽  
Tert Butyl Hydroperoxide ◽  
Aqueous Potassium Hydroxide ◽  
Butyl Peroxide

The preparation of dialkyl tert-butylperoxy phosphates (2, R = alkyl) has been achieved by the reaction of the corresponding dialkyl phosphorochloridates (1, R = alkyl) with tert-butyl hydroperoxide either in the presence of pyridine or in the presence of aqueous potassium hydroxide solution. Neither of these routes is suitable for the preparation of dialkyl tert-butylperoxy phosphates in quantity since they yield peroxyphosphates which are contaminated either with the corresponding tetraalkyl pyrophosphates or dialkyl phosphates; the contaminants cannot easily be removed by conventional means from the peroxyphosphates. The method of choice for the preparation in high yield of large quantities of pure dialkyl tert-butylperoxy phosphates involves the interaction of the corresponding dialkyl phosphorochloridate with sodium tert-butyl peroxide which has been prepared in situ from the reaction of tert-butyl hydroperoxide with sodium hydride.

KINETIC STUDIES OF THE AgO/Ag2O ELECTRODE IN ALKALINE SOLUTIONS

1964 ◽  
Vol 42 (11) ◽  
pp. 2488-2495 ◽  
Author(s):  
R. G. Barradas ◽  
G. H. Fraser
Keyword(s):  
Potassium Hydroxide ◽  
Potassium Hydroxide Solution ◽  
Kinetic Studies ◽  
Alkaline Solutions ◽  
Hyperbolic Function ◽  
Electron Number ◽  
Rate Determining Step ◽  
Symmetry Factor ◽  
Tafel Slopes ◽  
Aqueous Potassium Hydroxide

The anodic oxidation of Ag2O to AgO in normal aqueous potassium hydroxide solution was investigated quantitatively under both galvanostatic and potentiostatic conditions at 25 °C. A few results for similar experiments in N/40 KOH are also reported. Tafel slopes and other parameters were determined. The experimental results show the dependence of current density as a hyperbolic function of overpotential, i.e. i = 2i0 sinh (λFη/2RT). The electron number λ was found to be 2 and the symmetry factor β was confirmed to be 1/2. It is proposed that the rate-determining step for the formation of AgO from Ag2O occurs at the Ag2O/AgO interface and involves the transfer of O−2 ions.

Facile and Straightforward Synthesis of Racemic Version of Substituted 3-[3-(2-Hydroxyphenyl)-3-oxo-1-arylpropyl]-4-hydroxycoumarins: Easy Access to a Series of Biorelevant Warfarin Analogues

Synthesis ◽  
2021 ◽  
Author(s):  
Goutam Brahmachari ◽  
Mullicka Mandal ◽  
Indrajit Karmakar
Keyword(s):  
Potassium Hydroxide ◽  
Potassium Hydroxide Solution ◽  
Practical Method ◽  
Easy Access ◽  
Chromatographic Purification ◽  
Present Communication ◽  
Aqueous Potassium Hydroxide ◽  
Hydrolysis Of ◽  
Column Chromatographic ◽  
Operational Simplicity

AbstractThe present communication deals with a straightforward, efficient, and green synthesis of a series of racemic version of 3-[3-(2-hydroxyphenyl)-3-oxo-1-arylpropyl]-4-hydroxycoumarins as biologically interesting warfarin analogues upon decarboxylative hydrolysis of bis-coumarin derivatives in aqueous potassium hydroxide solution. The salient features of this practical method are operational simplicity, avoidance of any organic solvents and tedious column chromatographic purification, clean reaction profiles, excellent yields, and gram-scale synthetic applicability.

The construction of orientation-dependent crystal growth and etch rate functions II: Application to wet chemical etching of silicon in potassium hydroxide

2000 ◽  
Vol 87 (12) ◽  
pp. 8732-8740 ◽  
Author(s):  
E. van Veenendaal ◽  
J. van Suchtelen ◽  
W. J. P. van Enckevort ◽  
K. Sato ◽  
A. J. Nijdam ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Chemical Etching ◽  
Potassium Hydroxide ◽  
Etch Rate ◽  
Rate Functions ◽  
Wet Chemical ◽  
Wet Chemical Etching

Wet chemical etching of cadmium telluride photovoltaics for enhanced open-circuit voltage, fill factor, and power conversion efficiency

2019 ◽  
Vol 34 (24) ◽  
pp. 3988-3997 ◽  
Author(s):  
Ebin Bastola ◽  
Fadhil K. Alfadhili ◽  
Adam B. Phillips ◽  
Michael J. Heben ◽  
Randy J. Ellingson
Keyword(s):  
Power Conversion Efficiency ◽  
Cadmium Telluride ◽  
Chemical Etching ◽  
Fill Factor ◽  
Open Circuit Voltage ◽  
Power Conversion ◽  
Open Circuit ◽  
Wet Chemical ◽  
Wet Chemical Etching ◽  
Image Position

Abstract

scholarly journals Preparation of small silicon carbide quantum dots by wet chemical etching

2012 ◽  
Vol 28 (1) ◽  
pp. 44-49 ◽  
Author(s):  
David Beke ◽  
Zsolt Szekrényes ◽  
István Balogh ◽  
Zsolt Czigány ◽  
Katalin Kamarás ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Silicon Carbide ◽  
Chemical Etching ◽  
Wet Chemical ◽  
Wet Chemical Etching ◽  
Image Position

Abstract

scholarly journals Synthesis and Antimicrobial Activity of SomeNovel Benzimidazolyl Chalcones

2009 ◽  
Vol 6 (1) ◽  
pp. 196-200 ◽  
Author(s):  
B. A. Baviskar ◽  
Bhagyesh Baviskar ◽  
M. R. Shiradkar ◽  
U. A. Deokate ◽  
S. S. Khadabadi
Keyword(s):  
Antimicrobial Activity ◽  
Elemental Analysis ◽  
Spectroscopic Data ◽  
Potassium Hydroxide ◽  
Room Temperature ◽  
Potassium Hydroxide Solution ◽  
Aromatic Aldehydes ◽  
Plate Method ◽  
H Nmr ◽  
Aqueous Potassium Hydroxide

Some novel benzimidazolyl chalcones were synthesized by condensation ofN-(4-(1H-benzo[d]imidazol-2-yl)phenyl)acetamide with aromatic aldehydes in presence of aqueous potassium hydroxide solution at room temperature. All the synthesized compounds were characterized on the basis of their IR,1H NMR spectroscopic data and elemental analysis. All the compounds have been screened for antimicrobial activity by the cup-plate method.

scholarly journals Fabrication of Smooth GaN-Based Laser Facets

1999 ◽  
Vol 4 (S1) ◽  
pp. 799-804 ◽  
Author(s):  
D. A. Stocker ◽  
E. F. Schubert ◽  
K. S. Boutros ◽  
J. M. Redwing
Keyword(s):  
Chemical Etching ◽  
Field Effect ◽  
Etch Rate ◽  
Wet Etching ◽  
High Resistivity ◽  
Wet Chemical ◽  
Wet Chemical Etching ◽  
Image Position ◽  
P Type ◽  
Scanning Electron

A method is presented for fabricating fully wet-etched InGaN/GaN laser cavities using hotoenhanced electrochemical wet etching followed by crystallographic wet etching. Crystallographic wet chemical etching of n- and p-type GaN grown on c-plane sapphire is achieved using H3PO4 and various hydroxides, with etch rates as high as 3.2.μm/min. The crystallographic GaN etch planes are {0001}, {100}, {10}, {10}, and {103}. The vertical {100} planes appear perfectly smooth when viewed with a field-effect scanning electron microscope (FESEM), indicating a surface roughness less than 5 nm, suitable for laser facets. The etch rate and crystallographic nature for the various etching solutions are independent of conductivity, as shown by seamless etching of a p-GaN/undoped, high-resistivity GaN homojunction.

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