Thermodynamic Analysis and Kinetics of Etching of Thin PbS Films in Hydrochloric Acid Solutions

A hydrochloric acid solution of hydrogen peroxide was suggested for etching lead sulfide films. The solubility of lead sulfide in relation to the hydrochloric acid concentration in the etching solution was calculated using thermodynamic analysis, taking into account the stability of lead complex species. The kinetics of hydrogen peroxide decomposition in the hydrochloric acid solution was studied, and the formal rate equation of the process was constructed.     

Kinetics of Silicon Etching in Trifluoromethane Plasma

High Energy Chemistry - The kinetics of reactive ion etching of silicon in radiofrequency CHF3 plasma has been studied. It has been shown that with an increase in both power input into the...     

Inductively Coupled Plasma Etching in ICl- and IBr-Based Chemistries. Part I: GaAs, GaSb, and AlGaAs

High-density plasma etching of GaAs, GaSb, and AlGaAs was performed inICl/Ar and IBr/Ar chemistries using an Inductively Coupled Plasma (ICP)source. GaSb and AlGaAs showed maxima in their etch rates for both plamachemistries as a function of interhalogen percentage, while GaAs showedincreased etch rates with plasma composition in both chemistries. Etchrates of all materials increased substantially with increasing rf chuckpower, but rapidly decreased with chamber pressure. Selectivities >10 forGaAs and GaSb over AlGaAs were obtained in both chemistries. The etchedsurfaces of GaAs showed smooth morphology, which were somewhat better withICl/Ar than with IBr/Ar discharge. Auger Electron Spectroscopy analysisrevealed equirate of removal of group III and V components or thecorresponding etch products, maintaining the stoichiometry of the etchedsurface.     

Inductively Coupled Plasma Etching in ICl- and IBr-Based Chemistries. Part II: InP, InSb, InGaP, and InGaAs

A parametric study of Inductively Coupled Plasma (ICP) etching of InP, InSb, InGaP, and InGaAs has been carried out in ICl/Ar and IBr/Ar chemistries. Etch rates in excess of 3.1 for InP, 3.6 for InSb, 2.3 for InGaP, and 2.2 m/min for InGaAs were obtained in IBr/Ar plasmas. The ICP etching of In-based materials showed a general tendency: The etch rates increased substantially with increasing ICP source power and rf chuck power in both chemistries, while they decreased with increasing chamber pressure. The IBr/Ar chemistry typically showed higher etch rates than ICl/Ar, but the etched surface morphologies were fairly poor for both chemistries.     

Etching Mechanism of Pb(Zr,Ti)O3 Thin Films in Cl2/Ar Plasma

The etching mechanism of Pb(Zr,Ti)O₃ (PZT) thin films in Cl₂/Ar plasma was investigated through the analysis of gas mixing ratio on volume and surface chemistries. Experiments showed that PZT etch rate keeps a constant value up to 40% of Ar addition into Cl₂/Ar plasma. Langmuir probe measurement showed the noticeable influence of Cl₂/Ar mixing ratio on electron temperature and electron density. The modeling of volume kinetics for neutral and charged particles indicated monotonic changes of both densities and fluxes of active species such as chlorine atoms and positive ions. The analysis of surface kinetics showed that PZT etch rate behavior may be explained by the combination of spontaneous and ion-assisted etch mechanisms.     

Etching Characteristics and Mechanisms of TiO2 Thin Films in HBr/Ar and Cl2/Ar Inductively-Coupled Plasmas

The TiO₂ etching characteristics and mechanisms in HBr/Ar and Cl₂/Ar inductively-coupled plasmas were investigated under fixed gas-mixing ratio and bias power conditions. It was found that in both systems, an increase in gas pressure from 4 to 10 mTorr results in a non-monotonic TiO₂ etching rate, while a variation of input power in the range 500–800 W causes a faster-than-linear acceleration of the etching process. Plasma diagnostics performed by Langmuir probes and zero-dimensional plasma modeling provided data on plasma parameters, steady-state densities, and fluxes of the active species on the etched surface. The model-based analysis of the etching mechanism showed that for the given set of processing parameters, the TiO₂ etch kinetics correspond to the transitional regime of ion-assisted chemical reaction in which a chemical-etch pathway dominates.     

Effect of Plasma and Control Parameters on SiC Etching in a C2F6 Plasma

Effects of radio frequency (RF) source power (plasma density) on silicon carbide etching are examined with variations in RF bias power, pressure, O₂ fraction, and gap spacing. The etching was conducted in a C₂F₆ inductively coupled plasma. Depending on parameters or plasma conditions, the etch rate varied quite differently. When the source power was varied, the bias power (ion energy) was strongly involved in determining the relative variation in the etch rate. Complex interactions between the parameters were ascertained by means of a predictive model. The model was obtained by using a neural network in conjunction with a 2⁵ full factorial experiment. Model behaviors were consistent with experimental ones. By correlating the etch rate to the DC bias, it was identified that the source power effect on the etch rate is significantly enhanced as the DC bias is maintained at relatively low values.     

An Auger Electron Spectroscopic Study of Ion and Plasma Etching of Thin Films Obtained by Plasma Activation of the Microdroplet Products of Thermal Degradation of Solid Polypropylene

The matrix properties of films obtained by plasma-enhanced deposition of the microdroplet products of thermal degradation of solid propylene (PEPP) were studied. The sample thickness was 120 nm, and the volume fraction of the dense phase was 10%. The rates of ion sputtering and the rates and some features of etching of the PEPP films at various plasma parameters were determined from the concentration profiles of the basic film-forming element (carbon) as obtained by Auger electron spectroscopy (AES) in combination with layer-by-layer sputtering by argon ions. It was shown that the films were highly uniform over the entire film depth down to the substrate. The oxygen concentration on the sample surface and over the film depth were determined after the plasma etching of the film in the residual air (the depth of penetration and formation of oxygen-containing groups did not exceed 30 nm). The alternation of interference colors on the PEPP surface observed in scattered light during the plasma etching was described. Comparison of the results obtained with the data for initial polypropylene made it possible to conclude that the matrix forming the basis of the PEPP coatings (90%) can be treated as a polymer-like structure.     

Deposition of Gallium Nitride Thin Films by MOCVD in Microwave Plasma

The deposition of GaN thin films in a nitrogen–hydrogen microwave plasma using Ga(CH ₃ ) ₃ as a gallium precursor was investigated. The deposit was identified as stoichiometric GaN by XPS and XRD. The substrate was dielectrically heated in the microwave discharge and the substrate temperature was lower than that in usual thermal MOCVD. The NH radicals, which were the primary N-atoms precursors, and fragments of Ga(CH ₃ ) ₃ were identified in the plasma by OES. The NH radical formation and the decomposition of Ga(CH ₃ ) ₃ in the plasma may be one of the reasons for the lower deposition temperature of GaN. The position dependence of the substrate temperature showed similar tendency as the position dependence of the electron temperature. The plasma state contributes to the deposition of GaN thin films. The deposited GaN exhibited a wide optical band gap of 3.4eV. Material highly oriented along the c axis was detected in the deposit, and a PL spectrum which has the band head at about 450 mm was obtained.     

Exciton Diffusion in Polyfluorene Copolymer Thin Films: Kinetics,Energy Disorder and Thermally Assisted Hopping

A series of {(9,9‐dioctylfluorene)_0.7?x‐(dibenzothiophene‐S,S‐dioxide)_0.3‐[4,7‐bis(2‐thienyl)‐2,1,3‐benzothiadiazole]_x} (PFS₃₀‐TBTx), where x represents the minor percentage of the red emitter 4,7‐bis(2‐thienyl)‐2,1,3‐benzothiadiazole (TBT) randomly incorporated into the copolymer backbone, is investigated in order to follow the energy transfer from PFS₃₀ to TBT moieties. The emission of the donor poly[(9,9‐dioctylfluorene)_0.7‐(dibenzothiophene‐S,S‐dioxide)_0.3 identified by PFS₃₀ and peaking at 450 nm, is clearly quenched by the presence of the red TBT chromophore emitting at 612 nm, with an isoemissive point observed when the spectra are collected as a function of temperature. A plot of the ratio between the TBT and PFS₃₀ emissions as a function of the reciprocal of temperature gives a clear linear trend between 290 and 200 K, with an activation energy of 20 meV and showing a turn over to a non‐activated regime below 200 K. Picosecond time‐resolved fluorescence decays collected at the PFS₃₀ and TBT emission wavelengths, show a decay of the PFS₃₀ emission and a fast build‐in, followed by a decay, of the TBT emission, confirming that the population of the TBT excited state occurs during the PFS₃₀ lifetime(～600 ps). The population of the TBT excited state occurs on a time regime around 150 ps at 290 K, showing an energy barrier of 20 meV that turns over to a non‐activated regime below 200 K in clear agreement with the steady‐state data. The origin of the activation barrier is attributed to the presence of physical and energetic disorder, affected by fast thermal fluctuations that dynamically change the energy landscape and control the exciton migration through the polymer density of states.     

两种表征金属有机双层膜络合和金属薄膜氧化反应动力学的方法

建立了两种新的薄膜反应动力学表征方法, 即透射光谱法和方块电阻法, 以克服传统动力学表征手段在薄膜体系氧化与络合反应过程中应用的局限性. 以透射光谱为表征手段, 得到了Ag/TCNQ(四氰基对醌二甲烷)金属有机双层薄膜的络合反应动力学曲线; 以方块电阻为表征手段, 得到了Cu薄膜的氧化反应动力学过程.     

化学浴沉积cawo4薄膜的动力学

对化学浴沉积法制备的CaWO4薄膜进行了动力学研究。采用Avrami-Erofeev方程进行计算,得到反应温度40~80℃和反应溶液pH值为8~12条件下,CaWO4薄膜的动力学方程。结合实验分析各动力学参数的变化,发现反应温度越高,反应速率常数k越大,薄膜趋向于自发形核生长;反应溶液pH值越高,反应速率常数k显著减小,Avrami指数n则几乎不变。结果可见,pH值对反应速率的影响大,而对成核和生长方式影响小。pH值对反应速率的影响主要在于改变了Ca-EDTA螯合体的络合稳定性,进而影响整个反应的进行速度。通过动力学研究可以明确反映反应参数对薄膜生长的影响,体现了薄膜生长过程的本质,有助于达到有效控制反应过程的目的。     

Models for Mechanisms and Kinetics of Polymer Aerosol Nucleation in a Uniform Plasma

Mathematical models and a system of identification indexes were developed for two different tentative mechanisms of gas-discharge polymerization, the stepwise (activation–recombination) and chain mechanisms. The kinetic behavior corresponds to a consecutive complex reaction or a parallel reaction in the former and in the latter case, respectively. These kinetic patterns remain unchanged regardless of any variation in the reaction rate coefficients. Thus, the pattern of kinetic behavior can serve as a sufficiently reliable and stable indicator of a chemical class of the mechanism of plasma-chemical synthesis.     

Plasma Treatment Enhanced Magnetic Properties in Manganese Doped Titanium Nitride Thin Films

The ferromagnetic manganese doped TiN films were grown by plasma assisted molecular beam epitaxy on MgO(001) substrates. The nitrogen concentration and the ratio of manganese at Ti lattice sites increase after the plasma annealing post treatment. TiN(002) peak shifts toward low angle direction and TiN(111) peak disappears after the post treatment. The lattice expansion and peak shift are mainly ascribed to the reduction of nitrogen vacancies in films. The magnetism was suppressed in as-prepared sample due to the pinning effect of the nitrogen vacancies at defect sites or interface. The magnetism can be activated by the plasma implantation along with nitrogen vacancies reduce. The decrease of nitrogen vacancies leads to the enhancement of ferromagnetism.     

薄膜表面等离子体光催化剂Ag@AgBr/CNT/Ni的制备和性能

用复合电沉积技术制备了Ag@AgBr/CNT/Ni表面等离子体薄膜催化剂,以扫描电镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman Spectra)、X射线光电子能谱(XPS)和紫外-可见漫反射光谱(UV-Vis DRS)对薄膜的表面形貌、晶体结构、化学组成和光谱特性进行了表征,在可见光照射下,用罗丹明B(RhB)作为模拟污染物对薄膜的光催化性质和稳定性进行测定,采用测定薄膜电化学阻抗谱(EIS)和向反应系统中加入活性物种捕获剂的方法对薄膜光催化机制进行探索。结果表明:最优工艺下制备的Ag@AgBr/CNT/Ni薄膜是由少量碳纳米管(CNT)和表面沉积纳米Ag粒子的AgBr晶体构成的复合薄膜。薄膜具有突出的表面等离子体共振效应、优异的光催化活性和良好的催化稳定性。光催化罗丹明B 20 min,Ag@AgBr/CNT/Ni薄膜的降解率是Ag@AgBr/Ni薄膜的1.32倍,是P25 TiO_2/ITO多孔薄膜的21.6倍。在保持光催化性能基本不变的前提下可循环使用5次。CNT的存在使薄膜电荷传导性能和光催化还原溶解氧的性能大幅增加,是所制薄膜相对于Ag@AgBr/Ni薄膜光催化性能提高的主要原因。提出了薄膜光催化罗丹明B的反应机理。     

薄膜表面等离子体光催化剂Ag@AgBr/CNT/Ni的制备和性能

用复合电沉积技术制备了Ag@AgBr/CNT/Ni表面等离子体薄膜催化剂,以扫描电镜（SEM）、X射线衍射（XRD）、拉曼光谱（Raman Spectra）、X射线光电子能谱（XPS）和紫外-可见漫反射光谱（UV-Vis DRS）对薄膜的表面形貌、晶体结构、化学组成和光谱特性进行了表征,在可见光照射下,用罗丹明B（RhB）作为模拟污染物对薄膜的光催化性质和稳定性进行测定,采用测定薄膜电化学阻抗谱（EIS）和向反应系统中加入活性物种捕获剂的方法对薄膜光催化机制进行探索。结果表明：最优工艺下制备的Ag@AgBr/CNT/Ni薄膜是由少量碳纳米管（CNT）和表面沉积纳米Ag粒子的AgBr晶体构成的复合薄膜。薄膜具有突出的表面等离子体共振效应、优异的光催化活性和良好的催化稳定性。光催化罗丹明B 20 min,Ag@AgBr/CNT/Ni薄膜的降解率是Ag@AgBr/Ni薄膜的1.32倍,是P25 TiO₂/ITO多孔薄膜的21.6倍。在保持光催化性能基本不变的前提下可循环使用5次。CNT的存在使薄膜电荷传导性能和光催化还原溶解氧的性能大幅增加,是所制薄膜相对于Ag@AgBr/Ni薄膜光催化性能提高的主要原因。提出了薄膜光催化罗丹明B的反应机理。     

Rapid screening of wines for total content of F-, Cl-, Br-, and S-organic compounds

A rapid direct method for determining the total content of heteroelement-containing organic compounds in dry white wine has been developed. The method involves the solvent extraction of these compounds, the removal of extractant outside the reactor, the oxidative conversion of the total concentrate of analytes at high temperature, and the analysis of the whole absorbate volume by ion chromatography. The detection limits for different elements ranged from 10^?6 to 10^?5 g/L for 1-mL wine samples and from 10^?7 to 10^?6 g/L for 10-mL wine samples. The possibility of identifying pesticides used in viniculture based on detecting the heteroelements present in the molecule is considered.     

Etching Characteristics and Mechanisms of Mo and Al2O3 Thin Films in O2/Cl2/Ar Inductively Coupled Plasmas: Effect of Gas Mixing Ratios

An investigation of etching behaviors for Mo and Al₂O₃ thin films in O₂/Cl₂/Ar inductively coupled plasmas at constant gas pressure (6 mTorr), input power (700 W) and bias power (200 W) was carried out. It was found that an increase in Ar mixing ratio for Cl₂/Ar plasma results in non-monotonic etching rates with the maximums of 160 nm/min at 60 % Ar for Mo and 27 nm/min at 20 % Ar for Al₂O₃. The addition of O₂ in the Cl₂/Ar plasma causes the non-monotonic Mo etching rate (max. 320 nm/min at 40–45 % O₂) while the Al₂O₃ etching rate decreases monotonically. The model-based analysis of etching kinetics allows one to relate the non-monotonic etching rates in Cl₂/Ar plasma to the change in the etching regime from the ion-flux-limited mode (at low Ar mixing ratios) to the neutral-flux-limited mode (for high Ar mixing ratios). In the Cl₂/O₂/Ar plasma, the non-monotonic Mo etching rate is probably due to the change in reaction probability.     

Pulsed-Spray Radiofrequency Plasma Enhanced Chemical Vapor Deposition of CuInS2 Thin Films

Thin films of CuInS₂ were grown on various substrates at a temperature of 523 K from two metal-organic precursors using radiofrequency plasma enhanced chemical vapor deposition (PECVD). Two precursor molecules, with different solubility properties, were dissolved in appropriate solvents and sprayed into the plasma region in the PECVD chamber. The resulting films were examined for atomic composition, growth rate, crystalline orientation, and uniformity. Films made from each precursor differed in thickness, atomic composition, and crystallinity. The uniformity of the film was fairly good from near the edge to the center of the substrate, and evidence for a chalcopyrite-like structure was found in several samples deposited from one of the precursor molecules.