Bromine In Methanol Research Articles

Halogens, alcohols and potassium permanganate extend the storability of hot pepper seeds (Capsicum annuum l.) under accelerated ageing conditions

ABSTRACT The feasibility of extending the storability of fresh hot pepper seeds, by modifying the storage atmosphere, using the respiration inhibitors and seed desiccants was examined. Halogens such as chlorine, bromine and iodine and methanol, ethanol and potassium permanganate were used for a period of 22 months under accelerated ageing conditions of high seed moisture and temperature. The various seed quality parameters - viability, vigour, speed of germination, seedling dry weight, and moisture content were evaluated. In the untreated control, decreased seed viability was observed within 10 months of storage. However, iodine and chlorine were proved effective in retaining high seed viability up to 90.7 and 88.0%, respectively, even after 22 months of storage. Chlorine treatment was able to retain the seed vigour (904.0), iodine (766.4), KMnO4 (754.4) and methanol (566.7) whereas the value of vigour index in control was 72.0. Chlorine and iodine were on par in their ability to maintain the speed of seed germination (25.2 and 24.8, respectively), followed by KMnO4 (20.2). Seedling dry weight was proved as a parameter not sensitive in estimating the seed quality since even after 22 months storage of seeds at atmospheres of chlorine, iodine, KMnO4 and methanol did not show any differences. KMnO4 sharply reduced the seed moisture content from 9.83 to 7.89% providing better storability over the control.

Impact of Surface Treatment on the Structural and Electronic Properties of Polished CdZnTe Surfaces for Radiation Detectors

We present the effects of surface treatments on the structural and electronic properties of chemomechanically polished Cd0.9Zn0.1Te before contact deposition. Specifically, polished CdZnTe (CZT) samples were treated with four distinct chemical etchants: (1) bromine methanol (BM), (2) bromine in lactic acid, (3) bromine in methanol followed by bromine–20% lactic acid in ethylene glycol, and (4) hydrochloric acid (HCl). The surface structure and surface electronic properties were studied with atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). AFM images showed that three of the four etchants significantly altered the surface morphology and structure of CZT. All etchants created smoother surfaces; however, all except HCl also introduced high densities of defects. HCl was found to not affect the surface structure. XPS measurements indicated that a thick, ∼3 nm to 4 nm, TeO2 layer formed about 1 h after etching; hence, it is very important to process devices immediately after etching to prevent oxide formation.

Cu2ZnSnSe4 films from binary precursors

The precursor stacked films of consistent binary chalcogenides (ZnSe, SnSe, CuSe) were deposited onto molybdenum covered soda-lime glass substrates by vacuum evaporation. Thermal treatments in SnSe2 or elemental selenium containing atmospheres were used for copper-zinc-tin-sulphide (CZTSe) formation. XPS investigations confirm the formation of CZTSe films homogeneous in bulk in both selenization atmospheres. At the same time, surface area composition of films selenized in Se and SnSe2 differed and the surface layer of CTZSe films selenized in SnSe2 atmosphere was tin–rich, containing separate phases of Se and SnSe2. The etching of CZTSe films with 1% Br2-MeOH (bromine in methanol) at the rate of 75 nm/s removed mainly metals from the surface films and left precipitates of Se on the surface. Solar cell structures with the efficiency of about 3% were developed using selenized and etched films.

An XPS study of bromine in methanol etching and hydrogen peroxide passivation treatments for cadmium zinc telluride radiation detectors

The performance of single crystal CdZnTe radiation detectors is dependent on both the bulk and the surface properties of the material. After single crystal fabrication and mechanical polishing, modification of the surface to remove damage and reduce the surface leakage current is generally achieved through chemical etching followed by a passivation treatment. In this work, CdZnTe single crystals have been chemically etched using a bromine in methanol (BM) treatment. The BM concentrations employed were 0.2 and 2.0 (v/v) % and exposure times varied between 5 and 120s. Angle resolved XPS and sputter depth profiling has been employed to characterize the surfaces for the different exposure conditions. A Te rich surface layer was formed for all exposures and the layer thickness was found to be independent of exposure time. The enriched Te layer thickness was accurately determined by calibrating the sputter rate against a CdTe layer of known thickness. For BM concentrations of 0.2 (v/v) % and 2 (v/v) %, the Te layer thickness was determined to be 1.3±0.2 and 1.8±0.2nm, respectively. The BM etched surfaces have subsequently been passivated in a 30wt.% H2O2 solution employing exposure time of 15s. The oxide layer thickness has been calculated using two standard XPS methodologies, based on the Beer–Lambert expression. The TeO2 thickness calculated from ARXPS data are slightly higher than the thickness obtained by the simplified Beer–Lambert expression. For BM exposures of 30–120s followed by a passivation treatment of 30wt. % H2O2 solution employing an exposure time 15s, the ARXPS method gave an average TeO2 thickness value of 1.20nm and the simplified Beer–Lambert expression gave an average thickness value of 0.99nm.

Scanning tunneling spectra for the etched surface of p-type HgCdTe

PDF HTML阅读 XML下载 导出引用 引用提醒 液相外延p型碲镉汞表面区与腐蚀凹坑的不同扫描隧道谱特征 DOI: 作者: 作者单位: 上海大学理学院物理系和微结构实验室,上海市上大路号,上海大学理学院物理系和微结构实验室,上海市上大路号,上海大学理学院物理系和微结构实验室,上海市上大路号,上海大学理学院物理系和微结构实验室,上海市上大路号,上海大学理学院物理系和微结构实验室,上海市上大路号,上海大学理学院物理系和微结构实验室,上海市上大路号 作者简介: 通讯作者: 中图分类号: 基金项目: 上海市重点学科建设无线电物理专项基金（S30105） Scanning tunneling spectra for the etched surface of ptype HgCdTe Author: Affiliation: Dept of Physics and Laboratory for Microstructures,Shanghai University,Dept of Physics and Laboratory for Microstructures,Shanghai University,Dept of Physics and Laboratory for Microstructures,Shanghai University;China,Dept of Physics and Laboratory for Microstructures,Shanghai University,China,Dept of Physics and Laboratory for Microstructures,Shanghai University,Dept of Physics and Laboratory for Microstructures,Shanghai University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:利用超高真空扫描隧道显微镜对经过溴甲醇溶液腐蚀处理的液相外延碲镉汞材料进行了表征.发现经过腐蚀处理（3%浓度，2.5 min）的样品表面出现高密度的凹坑结构，凹坑深度约几十纳米，横向尺度在几十到几百纳米之间.扫描隧道谱测量表明，腐蚀样品表面平坦区呈现较大表观带隙，需考虑针尖诱导的能带弯曲效应，而凹坑区在零偏压区的扫描隧道谱线则近似为线性变化，说明该区域包含较高的带隙态并直接参与隧穿，从而掩盖了带隙信息. Abstract:Ultrahigh vacuum scanning tunneling microscopy（STM） and spectroscopy （STS）were used to characterize Hg1-xCdxTe grown by liquidphase epitaxy (LPE) method. The sample was etched with 3% Brominemethanol in 2.5 minutes. The STM images display submicrometersized pit structures with depths ranging from a few tens to a few hundreds nanometers. The scanning tunneling spectra show a larger apparent gap than the energy band gap of the bulk material due to the tipinduced band bending effect. In contrast, the scanning tunneling spectra of the pits show a finite slope through zero volt, implying the contribution of high density of band gap states which blur out the band gap information. 参考文献 相似文献 引证文献

Structure and properties of a rare-topology [MnII4]-core complex with terminal bromido ligands

A rare-topology [Mn II 4 ]-core complex [Mn 4 Br 4 (ppko) 4 (CH 3 OH) 4 ] ( 1 ; ppkoH = phenyl 2-pyridyl ketoxime) was synthesized via a solvothermal route and characterized by X-ray diffraction, IR, EPR, ESI-MS and magnetic properties measurements. In 1 Mn 2+ ions are bridged with phenyl 2-pyridyl ketoxime ligands. Bromine atoms and methanol molecules are terminal ligands. A comparison is made to the reported analogues with different terminal ligands pattern.

Surface modification of bulk n-InAs (111)A etched in bromine–methanol

X-ray photoelectron spectroscopy, field emission scanning electron microscopy, Raman and photoluminescence spectroscopy were used to evaluate the surface properties of n-type InAs (111)A etched in a 1% Br–methanol solution. Etching completely removes the native oxides from the surface and enhances the photoluminescence response. The adsorption of bromine onto the InAs surface leads to the formation of In–Brx and As–Brx bonds (x = 1, 2, 3) as inferred from changes in the In 3d3/2;5/2 and As 3d core level binding energies. The etch rate is found to decrease due to strong anisotropic effects and the high volatility of the bromine species. A 1 min Br–methanol etch was found to enhance the photoluminescence intensity by a factor of 3, probably due to a reduction in the surface state density upon de-oxidation of the surface. This is thought to be due to reductions in the surface state density. The presence of native oxides enhances both the surface accumulation layer and the surface state density.

Influence of Thermal Treatments on In-depth Compositional Uniformity of CuIn(S,Se)2 Thin Films

CuIn(S,Se)2 thin films were prepared by thermal crystallization of co-sputtered Cu-In alloy precursors in S/Se atmosphere. In-depth compositional uniformity is an important prerequisite for obtaining device-quality CuIn(S,Se)2 absorber thin films. In order to figure out the influence of heat treatments on in-depth composition uniformity of CuIn(S,Se)2 thin films, two kinds of reaction temperature profiles were investigated. One process is “one step profile", referring to formation of CuIn(S,Se)2 thin films just at elevated temperature (e.g. 500 °C). The other is “two step profile", which allows for slow diffusion of S and Se elements into the alloy precursors at a low temperature before the formation and re-crystallization of CuIn(S,Se)2 thin films at higher temperature (e.g. first 250 °C then 500 °C). X-ray diffraction studies reveal that there is a discrepancy in the shape of (112) peak. Samples annealed with “one step profile" have splits on (112) peaks, while samples annealed with “two step profile" have relatively symmetrical (112) peaks. Grazing incident X-ray diffraction and energy dispersive spectrum measurements of samples successively etched in bromine methanol show that CuIn(S,Se)2 thin films have better in-depth composition uniformity after “two step profile" annealing. The reaction mechanism during the two thermal processing was also investigated by X-ray diffraction and Raman spectra.

Slow-Polishing Iodine-Based Etchant for CdTe and CdZnTe Single Crystals

We report on new etching solutions for treatment of CdTe and CdZnTe surfaces based on the iodine-emerging etchant composition KIO3–KI–citric acid (C6H8O7). CdTe samples with (111), (110), and (100) orientations, and also Cd1−xZnxTe (x = 0.04, 0.1) samples with (111), (110), (100), and (211) orientations were investigated. The dissolution rate was determined as a function of solution composition, etchant storage time, disc rotation speed, and temperature. It was established that this chemical dissolution is diffusion controlled. Study of the chemical composition and structure of (211)B Cd1−xZnxTe surfaces etched under different conditions was carried out. x-Ray photoelectron spectroscopy measurements showed that a stoichiometric surface was achieved after briefly heating the etched surface in a vacuum. Reflection high-energy electron diffraction measurements revealed a high-quality single-crystalline surface layer in samples etched with KIO3–KI–citric acid solutions as compared with those etched with a bromine–methanol treatment. The etching compositions were shown to be useful for controlled removal of semiconductor material, and also for chemical polishing of CdTe-based surfaces.

Improvement of Surface Passivation Homogeneity of Gallium Antimonide by Bromination

Etching and sulfuring are equally important process during the surface sulfur passivation of gallium antimopnide (GaSb) In this work, we described the effects of etching by certain proportion of bromine methanol solution instead of hydrochloric acid solution (acidification), which could lead to a improvement of surface passivation homogeneity of GaSb. The photoluminescence (PL) spectra and the atomic force microscope (AFM) morphology on GaSb are also indicated a good surface morphology.

Treatment of the surface of blanks for fabrication of CdZnTe-based detectors

The depth of the damaged layer forming on the surface of the CdZnTe crystals during standard mechanical treatment of them is determined by the microhardness measurement and chemical selective etching. The rates of chemical etching of the surface of the CdZnTe crystals in the solutions of bromine in methanol with various bromine concentrations are determined.

Influence of surface preparation on CdZnTe nuclear radiation detectors

High resolution X-ray diffraction (HRXRD), Atomic Force Microscope (AFM), Scanning Electron Microscope (SEM) techniques were used to characterize the surface of CdZnTe (CZT) samples treated by mechanical lapping, polishing and chemical etching processes. The results confirm that the etching process produces the highest intensity diffraction peak, and the best full-width-at-half-maximum (FWHM). Fourier Transform Infrared (FTIR) spectroscopy shows that fine polishing increases the infrared transmission of the CZT sample, while etching with 2% bromine methanol (BM) etching decreases the infrared transmission. Different etchants and concentrations were investigated by comparing the surface morphology and roughness. The bromine methanol etching has shown more flat surface with lower roughness than the other etchants.

Chemical Polishing of CdTe and CdZnTe in Iodine–Methanol Etching Solutions

Iodine-containing polishing etchants were tested on CdTe and Cd1−x Zn x Te surfaces with different orientations. The nature of the chemical dissolution of CdTe with (111)A, (111)B, (110), and (100) orientations in the I2–methanol solution was studied. It was established that this dissolution is diffusion controlled. Study of the chemical composition and structure of the (211)B Cd1−x Zn x Te surfaces etched under different conditions was carried out. X-ray photoelectron spectroscopy (XPS) measurements showed that a stoichiometric surface was achieved after short heating of the etched surface in vacuum. Reflection high-energy electron diffraction (RHEED) measurements reveal a high-quality single-crystalline surface layer in samples etched with iodine–methanol solutions as compared with bromine–methanol treatment.

Raman spectroscopic study of HgCdTe epilayers for infrared detector array fabrication

Micro-Raman spectroscopy was used to evaluate the surface quality of Hg 1− x Cd x Te ( x = 0.3) epitaxial layers polished with chemo-mechanical and free chemical etching processes. Raman technique has been employed to monitor the HgCdTe detector array fabrication process to ensure epilayer surface devoid of impurities and minimal damage. Chemical etching with bromine–methanol solution is seen to leave residual damage or non-stoichiometric HgCdTe surface layer indicated by an asymmetrical broadening and down shift in all Raman peaks. A peak at 112 cm −1 as defect mode or due to disordering on the epilayer surface has been noticed.

Morphology and electronic states of chemically treated CdZnTe surfaces

The morphology and electronic structure of chemically treated CdZnTe surfaces has been studied using atomic force microscopy and scanning tunneling microscopy/spectroscopy. Studies have been performed on wet chemically etched and passivated surfaces. Etching in bromine methanol solutions effectively removes surface damage after polishing and produces a hillock like structure. A number of surface electronic states are introduced, both donor-like and acceptor-like, and are attributed to various surface defects. Because of the amorphous nature of the surface, these states have tails that extend into the band gap and produces a very narrow surface band. Charge hopping across the narrow band gap is proposed to explain the high surface conductivity. Surfaces passivated in hydrogen peroxide show increased roughness and using atomic force microscopy, the evolution of the formation of an oxide layer has been observed. Additional acceptor-like surface states of higher energy are introduced and the surface band gap is found to increase, reducing the surface conductivity.

Chemical etching and surface oxidation studies of cadmium zinc telluride radiation detectors

AbstractCdZnTe (CZT) is commonly used as a radiation detector material and the surface properties are important as they influence detector performance. The surface chemistry is generally controlled through chemical etching and oxidation processes. In this paper, X‐ray photoelectron spectroscopy (XPS) is employed to investigate changes in the surface composition of single‐crystal Cd0.95Zn0.05Te samples after exposure to bromine in methanol (BM) chemical etching treatments and subsequent oxidation in air or 30% H2O2. BM treatment of CZT is found to result in a graded Te‐rich surface layer which increases in thickness as a function of BM concentration. Room‐temperature air oxidation of 0.2% BM‐treated CZT follows a logarithmic rate law. BM‐treated CZT exposed to 30% H2O2 for 30 s shows a linear increase in the TeO2 oxide thickness with increasing BM concentration up to a BM concentration of 1.5%. Above 2% BM concentration, the Te enrichment in the CZT surface region has reached saturation and is effectively pure Te. Copyright © 2010 John Wiley & Sons, Ltd.

Effect of Atmosphere on n-Type Hg1–x Cd x Te Surface after Different Wet Etching Treatments: An Electrical and Structural Study

The impact on surface recombination velocity (SRV) and minority carrier lifetime of three wet etchants are examined here. The etchants are 60DI + 10HBr + 1H2O2 (by volume), 1% bromine–methanol, and 2% bromine–lactic acid. After initial etching, the HgCdTe surfaces were exposed in specific time steps to the atmosphere. At each step in the process, the effect of each etchant and of exposure to atmosphere was determined by photoconductive decay (PCD) measurements as well as by x-ray photoelectron spectroscopy (XPS). The PCD results showed that the 60DI + 10HBr + 1H2O2 etchant, after exposure to atmosphere, led to a relatively small change in SRV compared to the changes that occurred for the two bromine-based etchants. In addition, XPS measurements showed that there were no neutral tellurium inclusions in the case of 60DI + 10HBr + 1H2O2 and that TeO2 formed strictly out of tellurium bonded to HgCdTe. Moreover, TeO2 formed at a much slower rate on surfaces etched with HBr compared with those etched with the bromine-based etchants. A model is proposed in terms of band alignment at HgCdTe-Te0 and HgCdTe-TeO2 interfaces to explain the different surface recombination mechanisms that are due to different etchants and to atmospheric exposure.

Electrophilic aromatic addition reaction (AdEAr) to anthracene

Abstract After finding in a previous study that naphthalene and quinoline can react via electrophilic aromatic addition reaction (AdEAr), we applied this to anthracene. When anthracene was reacted with bromine in methanol in the presence of NaHCO3 and pyridine, 9,10-dihydro-9,10-dimethoxyanthracene (2) was obtained in 82% yield in the absence of substitution products or oxidative demethylation products like anthraquinone. The same reaction in ethanol produced 9,10-diethoxy-9,10-dihydroanthracene (9) in much lower yield (45%). In addition, we investigated the reactivity of addition product 2. Treatment of 2 with DDQ in benzene at 65 °C for 12 h produced 9,10-dimethoxyanthracene (3) in 62% yield, and 2 was rapidly transformed to 9-methoxyanthracene (4) in methanolic NaOH in 10 min. Moreover, the acid-catalyzed aromatization of 2 in 1-propanol at 75 °C for 10 min gave 9-n-propoxyanthracene (8) in 65% yield.

Reaction of N-methylsulfonyl-and N-(p-tolylsulfonyl)-2-(cyclopent-1-en-1-yl)anilines with bromine in the presence of potassium thiocyanate and in methanol

The reactions of N-methylsulfonyl-and N-(p-tolylsulfonyl)-2-(cyclopent-1-en-1-yl)-6-methylaniline with molecular bromine in the presence of potassium thiocyanate gave N-methylsulfonyl-and N-(ptolylsulfonyl)-2-(5-isothiocyanatocyclopent-1-en-1-yl)-6-methylanilines. N-Methylsulfonyl-2-(cyclopent-1-en-1-yl)-6-methylaniline reacted with bromine in methanol in the presence of NaHCO3 or with CuBr2 in MeOH to afford N-methylsulfonyl-2-(5-methoxycyclopent-1-en-1-yl)-6-methylaniline. The reaction of N-methylsulfonyl-2-(5-isothiocyanatocyclopent-1-en-1-yl)-6-methylaniline with diethylamine led to the formation of N-methylsulfonyl-2-{5-[diethylamino(thioxo)methyl]aminocyclopent-1-en-1-yl}-6-methylaniline which was converted into 5-methyl-4-methylsulfonyl-2,3,3a,4-tetrahydrocyclopenta[b]indole by heating with potassium hydroxide.

Interface properties of HCF 2Cl annealed CdTe thin films for solar cells applications

CdTe thin films deposited on CdS/ZnO/ITO/glass by Closed Space Sublimation, before and after annealing in HCF 2Cl (Freon gas) were etched in Bromine methanol solution for several minutes. This procedure makes the whole thickness of the CdTe layer accessible for investigation. The possible diffusion of impurities from the annealing gas, Cl or F in particular, into the CdTe thin film has been studied by means of SEM-cathodoluminescence as well as the distribution of the CL emissions within the CdTe grains. The electrical properties of the cells, determined by I–V measurements in the dark and under illumination have been correlated to the microscopic observation.