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.     

[Ga(en)3][Ga3Se7(en)] · H2O: Ein Galliumchalkogenid mit Ketten aus [Ga3Se6Se2/2(en)]3–-Bicyclen

[Ga(en)₃][Ga₃Se₇(en)] · H₂O: A Gallium Chalcogenide with Chains of [Ga₃Se₆Se_2/2(en)]^3– Bicycles The new selenidogallate [Ga(en)₃][Ga₃Se₇(en)] · H₂O ( I ) was produced from a ethylendiamine suspension of Ga and Se at 130 °C. I crystallizes in the orthorhombic space group Pna2₁ with unit constants a = 1347.9(3) pm, b = 961.6(1) pm, c = 1967.6(4) pm and Z = 4. The crystal structure contains an anion so far not observed in gallium chalcogenides. It is built from [Ga₃Se₆Se_2/2(en)]^3– bicycles of three Ga^IIIL₄ tetrahedra (L = en, Se) connected via selenium corners to linear chains. The cations, Ga^III ions coordinated by three ethylendiamine in a distorted octahedral geometry are positioned in the holes of the hexagonal rod packing of these chains.     

Compounds in the system Cu2SeAs2Se3

The phase diagram Cu₂SeAs₂Se₃ was investigated by thermal and X-ray methods. Cu₂Se has a limited solubility for As₂Se₃ (5 mole% at 769 K). The stoichiometric compound Cu₃AsSe₃ exists between 696 and 769 K. Cu₄As₂Se₅, a phase at 66.6 mole% Cu₂Se, decomposes peritectically at 746 K. The narrow homogeneity range (4 mole% at 683 K) extends far into the ternary space. CuAsSe₂ also decomposes peritectically at 683 K. A degenerated eutectic between CuAsSe₂ and As₂Se₃ was found at 641 K. Single crystals of Cu₄As₂Se₅ were grown in a salt melt. A metastable modification of the high-temperature phase Cu₃AsSe₃ can be obtained by quenching. Cu₄As₂Se₅ (space group R3, lattice constants a = 1404.0(1) pm, c = 960.2(1) pm), Cu₆As₄Se₉, obtained by Cambi and Elli, and Cu₇As₆Se₁₃ of Takeuchi and Horiuchi are different versions of a sphalerite-type compound with a broad homogeneity range in the system CuAsSe. CuAsSe₂ is possibly monoclinic with lattice parameters of a = 946.5(1) pm, b = 1229.3(1) pm, c = 511.7(1) pm, and β = 98.546(4)°. The enthalpy of mixing of Cu₂Se and As₂Se₃ in the liquid state is endothermic.     

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。     

The crystal structure of β-Ga2Se3

From new X-ray powder diffraction data reported in this paper, the structure of the ordered, superstructural phase of Ga₂Se₃ is found to be different from the structures stated in the literature up to now. The difference relates essentially to the structure distortion involved in the formation of the superstructure. This distortion is clarified in a way which, in general, is suitable for investigations of small distortions of cubic structures. The superstructure cell turns out to be monoclinic, with a = 6.6608(3), b = 11.6516(4), c = 6.6491(3) Å, β = 108.840(5)°, and Z = 4. Furthermore, the coordinates of the Ga and Se positions in this cell are deduced. The space group is shown to be C⁴_s-Cc (No. 9).     

Synchrotron-radiation photoemission study of the V–VI layered compounds Bi2Te3, Bi2Se3, Sb2 Te3 and Sb2Te2Se

The valence band (VB) density of states and the binding energies of the weakly bound core levels have been measured by XUV photoelectron spectroscopy using synchrotron radiation for four V–VI layered compounds. Chemical shifts of the core levels are determined which support the partial ionicity of the bonds involved. The chemical shifts of the emission from two unequivalent crystal sites were shown to differ by less than 30 meV for the compounds Bi₂Te₃, Bi₂Se₃ and Sb₂Te₃.VB and core-level photoemission spectra for the V–VI compounds Bi₂Te₃, Bi₂Se₃, Sb₂Te₃ and Se₂Te₂Se have been presented. Chemical shifts of the Te 4d, Bi 5d, Sb 4d and Se 3d levels were determined, indicating partial ionicity of the mainly covalent bonds involved. Chemical-shift differences originating from atoms at two different crystal sites are <30 meV. In a simple model this implies that similar charge transfers do occur even though completely different bond orbitals were proposed for the and the AB⁽²⁾ bonds. Finally, the fact that no surface core-level shifts were observed tends to confirm the very weak influence of the van der Waals-like bonds on the B⁽²⁾ atoms.     

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。     

Room temperature formation of Cu3Se2 by solid-state reaction between α-Cu2Se and α-CuSe

Upon being brought into contact with each other, α-Cu₂Se and α-CuSe pellets reacted entirely forming Cu₃Se₂ at room temperature. After 10 days, the reaction was almost completed. Weight measurements revealed that copper atoms migrated from α-Cu₂Se to α-CuSe. Solid-state reactions were also observed in the (α-Cu₂Se+Cu₃Se₂) and (α-Cu₂Se+CuS) systems, but not in the (Cu₃Se₂+α-CuSe), (Cu₂S+CuS) and (α-CuSe+Cu₂S) systems. Therefore, the high ionic conductivity of copper ions in α- and β-Cu₂Se is considered to be responsible for the solid-state reactions observed in these systems.     

Phase relations in the TlXTl2Se systems (X = Cl,Br, I) and the crystal structure of Tl5Se2I

Each of the quasibinary systems TlClTl₂Se, TlBrTl₂Se, and TlITl₂Se contains a region of solid solution up to 18 mole% Tl₂Se, which decomposes peritectically. The mixed crystals can be explained by a statistical substitution of Se by two I atoms on the fourfold sites of the Tl₂Se lattice. Compounds of the type Tl₅Se₂X were derived by complete substitution. Crystals of Tl₅Se₂I, suitable for a crystal structure determination, were grown by the Bridgman technique. Tl₅Se₂I is tetragonal, $\text{I4}\text{mcm}\text{; a = 866.3}\text{pm}\text{, c = 1346.3}\text{pm}\text{, Z = 4}$. The structure is an ordered variation of the In₅Bi₃ structure and isopuntal to the Cr₅B₃ type. The structure is formed basically by layers of Tl₂Se, in which strings of TlI are introduced. The compounds Tl₅Se₂Br (a = 861.1 pm, c = 1292.2 pm) and Tl₅Se₂Cl (a = 856.5 pm, c = 1273.3 pm) have probably very similar structures. A tendency for immiscibility in the TlXTl₂Se systems is shown by the existence of a miscibility gap in the system TlClTl₂Se and by the endothermic enthalpies of mixing in the system TlBrTl₂Se. In the TlITl₂Se system the compound Tl₆Se₄I system was encountered.     

Palladium site ordering and the occurrence of superconductivity in Bi2Pd3Se2−xSx

The crystallographic and electronic structures of compounds related to parkerite (Bi₂Ni₃S₂) are investigated with respect to the recently reported occurrence (Bi₂Pd₃Se₂) and absence (Bi₂Pd₃S₂) of superconductivity. Similarities and differences of the crystal structures are discussed within the series of solid solutions Bi₂Pd₃S_2−xSe_x from powder and single crystal diffraction data. From crystal structure refinements, the question of different structures and settings of parkerite is discussed. Similar and different 2D and 3D partial Pd-Ch (Ch=S, Se) structures are related to half antiperovskite ordering schemes. To investigate the relation of low dimensional structures and the occurrence of superconductivity, electronic structures are analyzed by scalar-relativistic DFT calculations, including site projected DOS, ECOV and Fermi surfaces.     

Preparation of Ga<Subscript>2</Subscript>Se<Subscript>3</Subscript> thin films by sol–gel technique

In this study we describe the preparation of Ga₂Se₃ semiconductor compound thin films by sol–gel method for different crystal formation temperatures. The films were characterized by X-ray diffraction analyses (XRD), UV–visible spectrometer, and scanning electron microscope (SEM). The XRD spectrum showed that the formation of Ga₂Se₃ crystals were between 743 and 823 K. The thin film crystals that were formed at 773 K corresponded to the β phase and the preferred crystal structure was monoclinic. The value of band gap from optical absorption spectra for the Ga₂Se₃ thin films was estimated to be about E _g ~ 2.56 eV. The thickness of the one-coat Ga₂Se₃ thin films, which was measured by a Spectroscopic Ellipsometer, was about ~200 nm. The average grain sizes of scattered particles were within the limits between 200 and 500 nm.     

Interactions and glass formation in the TlAs2Se4-Tl3As2Se3Te3 system

The TlAs₂Se₄-Tl₃As₂Se₃Te₃ system was studied using differential thermal analysis (DTA), powder X-ray diffraction, microstructure observation, and microhardness and density measurements. A phase diagram of the title system was constructed. This system is a quasi-binary join of the TlSe-As₂Se₃-As₂Te₃ quasi-ternary system. All alloys of the system under standard conditions are prepared in the glassy form. The system has a eutectic, which contains 50 mol % Tl₃As₂Se₃Te₃ and melts at 150°C. The TlAs₂Se₄-base solid solution in the system extends to 12 mol % Tl₃As₂Se₃Te₃, and Tl₃As₂Se₃Te₃-based solid solution extends to 20 mol % TlAs₂Se₄.     

Phase equilibria and glass formation in the As2S3-TlAs2S2Se2 section of the As2S3-As2Se3-TlS system

Alloys in the As₂S₃-TlAs₂S₂Se₂ section of the As₂S₃-As₂Se₃-TlS ternary system were studied and a phase diagram was constructed using physicochemical methods (differential thermal analysis, microstructural analysis, X-ray powder diffraction, also microhardness and density measurements). The diagram in the As₂S₃-TlAs₂S₂Se₂ section is a non-quasi-binary diagonal section of the As₂S₃-As₂Se₃-TlSe quasi-ternary system. It was found that all the alloys in the section under ordinary conditions are obtained in the vitreous state. At low As₂S₃ concentrations in the section, solid solutions form up to 2.5 mol %, and at low TlAs₂S₂Se₂ concentrations, their extent is 3 mol %.     

Interaction in the Ga2S3-Y2O2S system

The phase diagram of the Ga₂S₃-Y₂O₂S system has been investigated by differential thermal, X-ray powder diffraction, microstructural, and thermodynamic analyses. It has been established that the system is eutectic, and solubility at 295 K from the Ga₂S₃ side reaches 3 mol % Y₂O₂S. The coordinates of the eutectic point are 14 mol % Y₂O₂S and 1320 K.     

Phase diagram of the In3As2Se6-In3As2S3Se3 system

The In₃As₂Se₆-In₃As₂S₃Se₃ system has been investigated by methods of physicochemical analysis (DTA, X-ray powder diffraction, MSA) and by microhardness and density measurements. The phase diagram of the system, which is the quasi-binary section of the As-In-S-Se quaternary system, has been constructed. The region of the In₃As₂Se₆-based solid solutions is extended to 7 mol %, and the In ₃As₂S₃Se₃-based region to 15 mol %. A new quaternary compound In₆As₄S₃Se₉ is found in the system. Original Russian Text ? I.I. Aliev, R.S. Magammedragimova, A.A. Farzaliev, Dzh. Veliev, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 4, pp. 691–694.     

Metal Precursor Influence on Performance of CuIn1-xGaxSe2 Films

CuIn_1-xGa_xSe₂ (CIGS) films were prepared by a two-stage method, in which Cu-In-Ga metallic precursors were firstly deposited on unheated Mo-coated soda lime glass substrates by direct current sputtering CuGa (20%Ga) and radio frequency sputtering In targets inan Ar atmosphere, followed by selenization at 520 oC for 40 min in Se vapor. By adjust-ing the sputtering thickness ratio of surface CuGa (20%Ga) and bottom CuGa (20%Ga) alloy layers in metal precursor, different CIGS thin films were fabricated. Through X-ray diffraction spectra, Raman spectra, local energy dispersive spectrometer, planar- and cross-sectional views of scanning electron microscopy measurements, it revealed that the CIGS thin films from selenization of metal precursor with CuGa:In:CuGa thickness ratio of 7:20:3 (sample-2-se) was of chalcopyrite structure with the preferred (112) orientation, and the grains sizes ranged from 0.5 μm to 2 μm, and sample-2-se had no binary compound phase of In-Se and order defect compound phase. Consequently, the results of illuminated current-voltage curve and quantum efficiency measurements showed that the CIGS film device made from sample-2-se had relative higher photo-electric conversion efficiency (3.59%) and good spectrum response.     

Thermochemische Untersuchungen zum System Bi/Se/O. I. Das Phasendreieck Bi2Se3/Bi2O2Se/Se

Thermochemical Investigation on the System Bi/Se/O. I The Phase Triangle Bi₂Se₃/Bi₂O₂Se/Se By total pressure measurements of compositions in the subsystem Bi₂Se₃/Bi₂O₂Se/Se was shown, that in thermodynamic equilibrium the three phases Bi₂Se₃/Bi₂O₂Se/Se coexist. The barogram of the triangle reduces to the barogram of the line Bi₂Se₃? Se, the compound Bi₂O₂Se is not from influence of the total pressure in the investigated temperature range.     

An investigation of structural parameters and magnetic and optical properties of EuLn2Q4 (Ln=Tb-Lu, Q=S, Se)

EuLn₂Q₄ (Ln=Tb-Lu; Q=S, Se) has been synthesized using Sb₂Q₃ (Q=S, Se) fluxes at 1000 °C. These compounds crystallize in a CaFe₂O₄-type three-dimensional channel structure that is built from edge-shared double rutile chains of [LnQ₆] octahedra running down the b-axis. Each double chain is connected at the vertices to four other double chains to form open channels where bicapped trigonal prismatic Eu²⁺ ions reside. All of these compounds show antiferromagnetic ordering with Neel temperatures, T_N∼3-4 K. The optical band gaps for EuTb₂Se₄, EuDy₂Se₄, EuHo₂Se₄, EuEr₂Se₄, EuTm₂Se₄, EuYb₂Se₄ EuLu₂Se₄, and EuYb₂S₄ are found to be 2.0, 1.8, 1.8, 1.7, 1.8, 1.3, 1.7, and 1.6 eV, respectively.