离子液体电沉积CuInxGa1-xSe2薄膜

采用循环伏安法(CV)对离子液体Reline中三元CuCl₂+InCl₃+SeCl₄体系和四元CuCl₂+InCl₃+GaCl₃+SeCl₄体系的电化学行为进行了研究。研究表明,In³⁺并入三元CIS(Cu-In-Se)薄膜体系和Ga³⁺并入四元CIGS(Cu-In-Ga-Se)薄膜体系均有两种途径：一是发生共沉积,二是直接还原。利用电感耦合等离子体发射光谱(ICP)和扫描电镜(SEM)对沉积电势、镀液温度和主盐浓度对CIGS薄膜组成、镀层表面形貌的影响进行了测试,结果表明通过工艺参数的选择可以控制Ga/(Ga+In)和CIGS薄膜组成并得到化学计量比为Cu_1.00In_0.78Ga_0.27Se_2.13的薄膜。     

离子液体电沉积CuIn_xGa_(1-x)Se_2薄膜(英文)

采用循环伏安法(CV)对离子液体Reline中三元CuCl2+InCl3+SeCl4体系和四元CuCl2+InCl3+GaCl3+SeCl4体系的电化学行为进行了研究。研究表明,In3+并入三元CIS(Cu-In-Se)薄膜体系和Ga3+并入四元CIGS(Cu-In-Ga-Se)薄膜体系均有两种途径:一是发生共沉积,二是直接还原。利用电感耦合等离子体发射光谱(ICP)和扫描电镜(SEM)对沉积电势、镀液温度和主盐浓度对CIGS薄膜组成、镀层表面形貌的影响进行了测试,结果表明通过工艺参数的选择可以控制Ga/(Ga+In)和CIGS薄膜组成并得到化学计量比为Cu1.00In0.78Ga0.27Se2.13的薄膜。     

Prospect of determining copper sulfide nanoparticles by voltammetry: A potential artifact in supersaturated solutions

Certain natural waters appear to contain copper sulfide (Cu_xS) nanoparticles in nanomolar concentrations (as Cu). These nanoparticles have been tentatively identified by the characteristic pH below which they deposit sulfide onto Hg electrodes. A proposed alternate approach to studying Cu_xS nanoparticles relies on their hydrophobicity, which causes them to sorb to Hg electrodes; there they can undergo reduction at −0.9 to −1.1 V vs. Ag/AgCl. However, solutions supersaturated with respect to Cu sulfide phases also form Cu_xS directly at Hg electrode surfaces. The voltammetric reduction peaks obtained from these deposits are not clearly distinguishable from those obtained from sorbed nanoparticles. Surface formation of Cu_xS, which appears to be limited to approximately two layers, involves a reaction between Cu amalgam and electrodeposited HgS. Surface-formed Cu_xS could be problematic in studies of Cu_xS nanoparticles, but this obstacle can be avoided by conducting voltammetric accumulations at potentials too negative for HgS electrodeposition (e.g. −0.85 V). Electroreduction of surface-formed Cu_xS occurs by a two-dimensional instantaneous hole nucleation and growth process.     

Structural and optical properties of Ga2O3:In films deposited on MgO (1 0 0) substrates by MOCVD

Ga₂O₃:In films with different indium (In) content x [x=In/(Ga+In) atomic ratio] have been deposited on MgO (1 0 0) substrates by metalorganic chemical vapor deposition (MOCVD). Structural analyses revealed that the film deposited with actual In content (x′) of 0.09 was an epitaxial film and the films with x′=0.18 and 0.37 had mixed-phase structures of monoclinic Ga₂O₃ and bixbyite In₂O₃. The absolute average transmittance of the obtained films in the visible region exceeded 95%, and the band gap was in the range of 4.74-4.87 eV. Photoluminescence (PL) measurements were performed at room temperature, in which the visible luminescences were strong and could be seen by the naked eye. The strong emissions in the visible light region were proposed to originate from the gallium vacancies, oxygen deficiencies and other defects in these films.     

Deposition of copper‐doped iron sulfide (CuxFe1−xS) thin films using aerosol‐assisted chemical vapor deposition technique

Copper‐doped iron sulfide (Cu_xFe_1?xS, x = 0.010–0.180) thin films were deposited using a single‐source precursor, Cu(LH)₂Cl₂ (LH = monoacetylferrocene thiosemicarbazone), by aerosol‐assisted chemical vapor deposition technique. The Cu‐doped FeS thin films were deposited at different substrate temperatures, i.e. 250, 300, 350, 400 and 450 °C. The deposited thin films were characterized by X‐ray diffraction (XRD) patterns, Raman spectra, scanning electron microscopy, energy dispersive X‐ray analysis (EDX) and atomic force microscopy. XRD studies of Cu‐doped FeS thin films at all the temperatures revealed formation of single‐phase FeS structure. With increasing substrate temperature from 250 to 450 °C, there was change in morphology from wafer‐like to cylindrical plate‐like. EDX analysis showed that the doping percentage of copper increased as the substrate temperature increased from 250 to 450 °C. Raman data supports the doping of copper in FeS films. Copyright © 2010 John Wiley & Sons, Ltd.     

First Dinuclear Copper/Gallium Complexes: Supporting Cu0 and CuI Centres by Low‐Valent Organogallium Ligands

The synthesis and structural characterisation of low‐valent dinuclear copper(I) and copper(0) complexes supported by organogallium ligands has been accomplished for the first time by the reductive coordination reaction of [GaCp*] (Cp*=pentamethylcyclopentadienyl) and [Ga(ddp)] (ddp=HC(CMeNC₆H₃‐2,6‐iPr₂)₂ 2‐diisopropylphenylamino‐4‐diisopropylphenylimino‐2‐pentene) with readily available copper(II) and copper(I) precursors. The treatment of CuBr₂ and Cu(OTf)₂ (OTf=CF₃SO₃) with [Ga(ddp)] under mild conditions resulted in elimination of [Ga(L)₂(ddp)] (L=Br, OTf) and afforded the novel gallium(I)/copper(I) compounds [{(ddp)GaCu(L)}₂] (L=Br ( 1 ), OTf ( 2 )). The single‐crystal X‐ray structure determinations of 1 and 2 reveal that these molecules are composed of {(ddp)GaCu(L)} dimeric units, with planar Cu^I? Ga^I four‐membered rings and short Cu^I???Cu^I distances, with 2 exhibiting the shortest Cu^I???Cu^I contact reported to date of 2.277(3) Å. The all‐gallium coordinated dinuclear [Cu₂(GaCp*)(μ‐GaCp*)₃Ga(OTf)₃] ( 3 ) is formed when Cu(OTf)₂ is combined with [GaCp*] instead of [Ga(ddp)]. Notably, in the course of this redox reaction Lewis acidic Ga(OTf)₃ is formed, which coordinates to one of the electron‐rich copper(0) centres. Compound 3 is suggested as the first case of a structurally characterised complex of copper(0). By changing the copper(II) to a copper(I) source, that is, [Cu(cod)₂][OTf] (cod=1,5‐cyclooctadiene), the salt [Cu₂(GaCp*)₃(μ‐GaCp*)₂][OTf]₂ ( 4 ) is formed, the cationic part of which is related to previously described isoelectronic dinuclear d¹⁰ complexes of the type [M₂(GaCp*)₅] (M=Pd, Pt).     

Investigation of the interaction between Co sulfide coatings and Cu(I) ions by cyclic voltammetry and XPS

The interaction between the Co sulfide coating formed on a glassy carbon electrode and Cu(I)-ammonia complexes solution was investigated by cyclic voltammetry in 0.1 M KClO₄, 0.1 M NaOH and 0.05 M H₂SO₄ solutions. It was determined that, after treating the cobalt sulfide coating formed by two deposition cycles with Cu(I)-ammonia complexes (0.4 M, pH 8.8–9.0, τ=180 s, T=25±1°C), an exchange occurs between the coating components and Cu(I). Copper(I) substitutes 75% of the Co(III) compounds present in the coating (~1.81×10^–7 mol cm^–2) because of Cu₂O (1.36×10^–7 mol cm^–2) formation. The rest of the Co(II) and Co(III) sulfide compounds are also replaced by copper with formation of Cu_{2– x} S with a stoichiometric coefficient close to 2 (~1.9). After modifying the cobalt sulfide coatings with Cu(I) ions, the total amount of metal (Co+Cu) increases, owing to the sorption of Cu(I) compounds. In addition, the number of deposition cycles decreases from 3 to 1.5 [1 cycle involves cobalt sulfide layer formation and 0.5 cycle is attributed to modifying by Cu(I) ions]. The coatings modified in the above-mentioned manner may be successfully used for plastic electrochemical metallization as Cu_{2– x} S coatings formed by three deposition cycles. Electronic Publication     

Atomic Layer Deposition of Iron Sulfide and Its Application as a Catalyst in the Hydrogenation of Azobenzenes

The atomic layer deposition (ALD) of iron sulfide (FeS_x ) is reported for the first time. The deposition process employs bis(N ,N′ ‐di‐tert‐butylacetamidinato)iron(II) and H₂S as the reactants and produces fairly pure, smooth, and well‐crystallized FeS_x thin films following an ideal self‐limiting ALD growth behavior. The FeS_x films can be uniformly and conformally deposited into deep narrow trenches with aspect ratios as high as 10:1, which highlights the broad applicability of this ALD process for engineering the surface of complex 3D nanostructures in general. Highly uniform nanoscale FeS_x coatings on porous γ‐Al₂O₃ powder were also prepared. This compound shows excellent catalytic activity and selectivity in the hydrogenation of azo compounds under mild reaction conditions, demonstrating the promise of ALD FeS_x as a catalyst for organic reactions.     

Electroless Copper Sulfide Deposition on the Polyacrylonitrile Films with Chelating Agents and its EMI Shielding Effectiveness

In this study, an effective deposition of copper sulfide (Cu_{x(x = 1,2)}S) on the PAN film was proposed by an electroless deposition method with the reduction agents NaHSO₃ and Na₂S₂O₃ · 5H₂O and chelating agents (ethylenediaminetetraacetic acid, EDTA and triethanolamine, TEA). The mechanism of the Cu_{x(x = 1,2)}S growth and the electromagnetic interference shielding effectiveness (EMI SE) of the C_{ux(x = 1,2)}S/PAN films were studied. It was found that the vinyl acetate monomer residue in the PAN substrate would be purged due to the swelling effect by EDTA and TEA solution. And then, the anchoring effect occurred due to the hydrogen bonding between the pits of the PAN substrate and the chelating agent. The swelling degree (S_d) was proposed and evaluated from the FT-IR spectra. The relationship between swelling degree of the PAN films and EDTA concentration(C) is expressed as: S_d = 0.13 + 0.90 × eˆ(−15.15C_EDTA). And TEA series is expressed as: S_d = 0.07 + 1.00 × eˆ(−15.15C_TEA). On the other hand, the FESEM micrograph showed that the average thickness of copper sulfide increased from 76 nm to 383 nm when the concentration of EDTA increased from 0.00 M to 0.20 M. Consequently, the EMI SE of the C_{ux(x = 1,2)}S/PAN films increased from 10∼12 dB to 25∼27 dB. The GIA-XRD analyzer indicated that the deposited layer consisted of CuS and Cu₂S.     

Thermal decomposition of gallium nitrate hydrate Ga(NO<Subscript>3</Subscript>)<Subscript>3</Subscript>×<Emphasis Type="Italic">x</Emphasis>H<Subscript>2</Subscript>O

The thermal decomposition of gallium nitrate hydrate (Ga(NO₃)₃·xH₂O) to gallium oxide has been studied by TG/DTG and DSC measurements performed at different heating rates. It is concluded that 8 water molecules are present in the hydrate compound. The anhydrous gallium nitrate does not form at any temperature as the reaction consists of coupled dehydration/decomposition processes that occur with a mechanism dependent on heating rate. TG measurements performed with isothermal steps (between 31 and 115°C) indicate that Ga(OH)₂NO₃ forms in the first stage of the reaction. Such a compound undergoes further decomposition to Ga(OH)₃ and Ga(NO₃)O, compounds that then decompose respectively to Ga(OH)O and finally to Ga₂O₃ and directly to Ga₂O₃. Diffuse reflectance Fourier transform IR spectroscopy (DRIFTIR) has been of help in assessing that the reaction consists of parallel dehydration/decomposition processes.     

Syntheses, X-ray structures and CVD studies of diorganoalkoxogallanes

Structural studies by X-ray crystallography have been carried out for a range of diorganoalkoxogallanes incorporating donor-functionalized ligands. The compounds [Et₂Ga(μ-OR)]₂ (1, R = CH₂CH₂NMe₂; 2, R = CH(CH₃)CH₂NMe₂; 3, C(CH₃)₂CH₂OMe; 4, R = CH(CH₂NMe₂)₂) adopt dimeric structures with a planar Ga₂O₂ ring, and each gallium atom is coordinated in a distorted trigonal bipyramidal geometry. Low pressure chemical vapor deposition (CVD) of 2 and 4 resulted in the formation of oxygen deficient gallium oxide thin films on glass. However, the reaction of Et₃Ga and ROH (R = CH₂CH₂NMe₂, CH(CH₃)CH₂NMe₂, C(CH₃)₂CH₂OMe, CH(CH₂NMe₂)₂) in toluene under aerosol assisted (AA)CVD conditions afforded stoichiometric Ga₂O₃ thin films on glass. This CVD technique offers a rapid, convenient route to Ga₂O₃, which involves the in situ formation of diethylalkoxogallanes, of the type [Et₂Ga(μ-OR)]₂, the structures of which are described in this paper. The gallium oxide films were deposited at 450 °C and analyzed by scanning electron microscopy (SEM), X-ray powder diffraction, wavelength dispersive analysis of X-rays (WDX), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy.     

Synthesis and Structural Characterization of β‐Ketoiminate‐Stabilized Gallium Hydrides for Chemical Vapor Deposition Applications

Bis‐β‐ketoimine ligands of the form [(CH₂)_n{N(H)C(Me)?CHC(Me)?O}₂] (LⁿH₂, n=2, 3 and 4) were employed in the formation of a range of gallium complexes [Ga(Lⁿ)X] (X=Cl, Me, H), which were characterised by NMR spectroscopy, mass spectrometry and single‐crystal X‐ray diffraction analysis. The β‐ketoimine ligands have also been used for the stabilisation of rare gallium hydride species [Ga(Lⁿ)H] (n=2 ( 7 ); n=3 ( 8 )), which have been structurally characterised for the first time, confirming the formation of five‐coordinate, monomeric species. The stability of these hydrides has been probed through thermal analysis, revealing stability at temperatures in excess of 200 °C. The efficacy of all the gallium β‐ketoiminate complexes as molecular precursors for the deposition of gallium oxide thin films by chemical vapour deposition (CVD) has been investigated through thermogravimetric analysis and deposition studies, with the best results being found for a bimetallic gallium methyl complex [L³{GaMe₂}₂] ( 5 ) and the hydride [Ga(L³)H] ( 8 ). The resulting films ( F5 and F8 , respectively) were amorphous as‐deposited and thus were characterised primarily by XPS, EDXA and SEM techniques, which showed the formation of stoichiometric ( F5 ) and oxygen‐deficient ( F8 ) Ga₂O₃ thin films.     

Mechanochemical-thermal preparation and structural studies of mullite-type Bi2(GaxAl1−x)4O9 solid solutions

A series of Bi₂(Ga_xAl_1−x)₄O₉ solid solutions (0≤x≤1), prepared by mechanochemical processing of Bi₂O₃/Ga₂O₃/Al₂O₃ mixtures and subsequent annealing, was investigated by XRD, EDX, and ²⁷Al MAS NMR. The structure of the Bi₂(Ga_xAl_1−x)₄O₉ solid solutions is found to be orthorhombic, space group Pbam (No. 55). The lattice parameters of the Bi₂(Ga_xAl_1−x)₄O₉ series increase linearly with increasing gallium content. Rietveld refinement of the XRD data as well as the analysis of the ²⁷Al MAS NMR spectra show a preference of gallium cations for the tetrahedral sites in Bi₂(Ga_xAl_1−x)₄O₉. As a consequence, this leads to a far from random distribution of Al and Ga cations across the whole series of solid solutions.     

Effect of surface treatments on interfacial characteristics and band alignments of atomic‐layer‐deposited Al2O3 films on GaAs substrates

The GaAs surfaces were passivated by two kinds of chemical pretreatments (using NH₄OH and (NH₄)₂S as passivation agents) for atomic layer deposited (ALD) Al₂O₃ dielectric film growth. The chemical information at Al₂O₃/GaAs interfaces was carefully characterized. The impact of surface treatments on the band alignments of ALD Al₂O₃ films on n? GaAs (100) substrates was also investigated. After postdeposition annealing, the NH₄OH passivated samples not only have a slight increase of the As? As peaks with an appearance of As suboxide (AsO_x) feature at Al₂O₃/GaAs interfaces but also exhibit a serious interfacial interdiffusion between Al₂O₃ and GaAs. However, the (NH₄)₂S passivated samples produce the Ga? S and As? S overlayers on GaAs, effectively preventing from the intermixed diffusion between Al₂O₃ films and GaAs substrates with a sharper interface. Both NH₄OH and (NH₄)₂S passivated Al₂O₃ samples show the same band gap of 6.67 eV. The conduction band offset at Al₂O₃/GaAs interface for the (NH₄)₂S passivated samples have a slight enhancement of 0.14 eV in comparison to NH₄OH passivated ones. Copyright © 2010 John Wiley & Sons, Ltd.     

Formation and characterization of Cu<Subscript>x</Subscript>S layers on polyethylene film using the solutions of sulfur in carbon disulfide

Results of the formation of copper sulfide layers using the solutions of elemental sulfur in carbon disulfide as precursor for sulfurization are presented. Low density polyethylene film can be effectively sulfurized in the solutions of rhombic (α) sulfur in carbon disulfide. The concentration of sulfur in polyethylene increases with the increase of the temperature and concentration of sulfur solution in carbon disulfide and it little depends on the duration of sulfurization. Electrically conductive copper sulfide layers on polyethylene film were formed when sulfurized polyethylene was treated with the solution of copper (II/I) salts. Cu_xS layer with the lowest sheet resistance (11.2 Ω cm⁻²) was formed when sulfurized polyethylene was treated with copper salts solution at 80°C. All samples with formed Cu_xS layers were characterized by X-ray photoelectron spectroscopy. XPS analysis of obtained layers showed that on the layer’s surface and in the etched surface various compounds of copper, sulfur and oxygen are present: Cu₂S, CuS, CuO, S₈, CuSO₄, Cu(OH)₂ and water. The biggest amounts of CuSO₄ and Cu(OH)₂ are present on the layer’s surface. Significantly more copper sulfides are found in the etched layers.     

Corrosion of copper electrode in sodium sulfide solution

The electrochemical reactions of a copper electrode in Na₂S solutions were studied using cyclic voltammetry, potentiostatic and galvanostatic measurements. In addition surface examination and morphological studies were applied using scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX). There are three anodic peaks were found in the anodic branch of the voltammogram’s. These peaks may be corresponding successively to the formation of Cu₂S, CuS and Cu₂O. On the other hand, the cathodic branch contains four peaks. These peaks correspond to the reduction of copper oxide and copper sulfide formed on the anodic branch.     

A crystallographic description of experimentally identified formation reactions of Cu(In,Ga)Se2

This work describes solid-state reactions for the formation of the chalcopyrite compounds CuInSe₂, CuGaSe₂ and Cu(In,Ga)Se₂ on atomic scale. The most important chalcopyrite formation reactions which were identified by the authors by real-time in situ X-ray diffraction in preceding experiments are (A) CuSe+InSe→CuInSe₂, (B) Cu₂Se+2 InSe+Se→2 CuInSe₂ and (C) Cu₂Se+In₂Se₃→2 CuInSe₂. During the selenistaion of a metallic precursor containing gallium a separate fourth reaction occurs: (D) Cu₂Se+Ga₂Se₃→2 CuGaSe₂. The quaternary compound is finally formed by interdiffusion of CuInSe₂ with CuGaSe₂ (E). These five reactions differ in their activation energy and reaction speed. We explain these differences qualitatively by analysing the involved crystal structures for each reaction. It turns out that all reactions involved in the formation of Cu(In,Ga)Se₂ are promoted by epitaxial relations, which facilitates the formation of polycrystalline thin films at temperatures much below those necessary for single crystal growth. Recommendations for the growth of larger grains of Cu(In,Ga)Se₂ containing fewer defects are given.     

Structural investigation of the Cu2Se-In2Se3-Ga2Se3 phase diagram, X-ray photoemission and optical properties of the Cu1−z(In0.5Ga0.5)1+z/3Se2 compounds

Structures of compounds in the Cu₂Se-In₂Se₃-Ga₂Se₃ system have been investigated through X-ray diffraction. Single crystal structure studies for the so-called stoichiometric compounds Cu(In,Ga)Se₂ (CIGSe) confirm that the chalcopyrite structure (space group I4¯2d) is very flexible and can adapt itself to the substitution of Ga for In. On the other hand a structure modification is evidenced in the Cu_1−z(In_0.5Ga_0.5)_1+z/3Se₂ series when the copper vacancy ratio (z) increases; the chalcopyrite structure turns to a modified-stannite structure (I4¯2m) when z≥0.26. There is a continuous evolution of the structure from Cu_0.74(In_0.5Ga_0.5)_1.09Se₂ to Cu_0.25(In_0.5Ga_0.5)_1.25Se₂ ((i.e. Cu(In_0.5Ga_0.5)₅Se₈), including Cu_0.4(In_0.5Ga_0.5)_1.2Se₂ (i.e. Cu(In_0.5Ga_0.5)₃Se₅). From this single crystal structural investigation, it is definitively clear that no ordered vacancy compound exists in that series. X-ray photoemission spectroscopy study shows for the first time that the surface of powdered Cu_1−z(In_0.5Ga_0.5)_1+z/3Se₂ compounds (z≠0) is more copper-poor than the bulk. The same result has often been observed on CIGSe thin films material for photovoltaic applications. In addition, optical band gaps of these non-stoichiometric compounds increase from 1.2 to 1.4 eV when z varies from 0 to 0.75.     

Kinetics of Oxidation Processes in the System Co/Ga studied by in situ X‐Ray Diffraction

Oxidation processes in the system Co/Ga were studied by in situ X‐ray diffraction at temperatures between 800 and 1000 °C. Experiments were performed with metal powders and planar substrates. Oxidation of cobalt‐rich alloys, Co_1‐xGa_x, results in the formation of mixtures of cobalt‐ and gallium‐containing oxides. During oxidation of the intermetallic compounds CoGa and CoGa₃ only gallium is oxidized, and dense tarnishing layers of β‐Ga₂O₃ are formed. In all cases the oxide products are only intermediate products on the way to thermodynamic equilibrium, i.e. total oxidation of both metals. The kinetics during oxidation of the intermetallic compound CoGa was studied in detail by time resolved in situ X‐ray diffraction. After an induction time the kinetics can be described by a parabolic rate law with an activation energy of 312 kJ mol^—1. From the decrease of the parabolic rate constant with decreasing oxygen partial pressure and the observation of pore formation at the metal‐oxide interface it can be concluded that (i) outward diffusion of Ga‐ions through β‐Ga₂O₃ is the rate determining step during this solid state reaction, and (ii) Ga‐ions are mobile by means of gallium vacancies.