Elemental Indium Research Articles

The Variations of Cu/Ga Ratio on the Structural and Optical Properties of Cu(In, Ga)Se<sub>2</sub> Thin Films by Co-Evaporation Technology

The result of an extensive research on this material is the achievement of approaching 20% efficiency by the co-evaporation of copper, indium, gallium and selenium elements. Recently, photoluminescence (PL) spectra have been studied on Cu (In,Ga) Se2 (CIGS) thin films and CIGS solar cells, to clarify the carrier recombination process. The CIGS layers were grown on the Mo-coated soda-lime glass substrate by the three stage process and four sources co-evaporation of constituent elements onto a heated substrate. It has found that the structural and optical properties of the CIGS thin film was influenced by the Cu/Ga ratio (RCu/Ga) of the CIGS thin film compositional variation. The X-ray diffraction and PL spectra were used to characterize the structure property and carrier recombination mechanism of CIGS thin film.

High-pressure torsion of pure metals: Influence of atomic bond parameters and stacking fault energy on grain size and correlation with hardness

The grain size in pure elements (magnesium, aluminum, silicon, titanium, vanadium, chromium, iron, nickel, copper, zinc, germanium, zirconium, niobium, molybdenum, palladium, silver, indium, tin, hafnium, tantalum, gold and lead) after processing by high-pressure torsion (HPT) reaches steady-state levels where the grain size remains unchanged with straining. The steady-state grain sizes decrease by atomic bond energy and related parameters such as specific heat capacity, activation energy for self-diffusion and homologous temperature and are reasonably independent of stacking fault energy. A good correlation exists between the hardness normalized by the shear modulus and grain size normalized by the Burgers vector, indicating that the important factor for strengthening HPT-processed pure metals is the average size of grains having high angles of misorientation.

Development of Ag based brazing filler metal with low melting point

This study was carried out to develop cadmium free silver based brazing filler metals that meet the following requirements. First, they have to have a melting point lower than that of BAg-1 brazing filler metal. Second, they have to have not only good wetting characteristics and the ability to produce a sound joint with excellent mechanical properties but also plastic formability. Using the calculated phase diagrams on Ag–Cu–Zn–Sn quaternary system alloys, the authors selected several alloys with a possibility of meeting the above requirements. The melting point and other properties, such as hardness and brazeability of the selected alloys, were evaluated. As a result, the authors successfully developed silver based brazing filler metals that have a low melting point below ∼600°C and meet the above requirements by adding a small amount of indium as an alloying element into the Ag–Cu–Zn–Sn quaternary system alloy. The newly developed brazing filler metals are slightly inferior in wetting characteristics to BAg-1; however, the brazing filler metal containing ∼3 mass-% indium element showed wetting characteristics comparable to those of BAg-1. Furthermore, the new brazing filler metals could produce joints with a high tensile strength equivalent to ∼83% of that of a joint brazed using BAg-1.

Synthesis and Characterization of CuInS<sub>2</sub> and CuInSe<sub>2</sub> Compounds by Vacuum Sintering Method

We report herein synthesis and characterization of CuInS2and CuInSe2compounds by vacuum sintering method. In this study, the manual-milled and ball-milled precursors including copper, indium, and sulfur (selenium) elements were sintered under vacuum at different temperatures for synthesis of CuInS2and CuInSe2compounds, respectively. The crystal structure, morphology and Raman property of the sintered powder were investigated by X-ray diffraction, scanning electron microscope and Raman scattering spectroscopy, respectively. The results show that the structure of the products, which was sintered with the manual-milled and ball-milled precursors, were transformed into the single chalcopyrite phase CuInS2powder at 923K and 623K, and the grain size are about 2～3μm and 250 nm, respectively. In addition, the CuInSe2 powder was synthesized about 723K via using the ball-milled powder including copper, indium, and selenium elements as the precursor.

Neutral Carbene Analogues of Group 13 Elements: The Dimerization Reaction to a Biradicaloid

The dimerization reactions of the neutral carbene analogues with the group 13 elements boron, aluminum, gallium, and indium are studied. Besides boron, all monomeric species possess singlet ground states. For Al, bulky substituted cases were investigated; they reveal no essential changes in the singlet-triplet energy separations compared with the parent species. The dimerization energies increase with an increase in the bulk of the substituents; this is a consequence of an enhancement of van der Waals forces for association. The latter is opposed by entropic forces, which facilitate dissociation. An equilibrium between monomeric and dimeric structures is predicted because of enthalpy versus entropy control. The low-temperature domain association should prevail in the formation of a dimer with Al (Ga) within the formal oxidation state I+. The Al-Al bond refers to a chelated biradicaloid species with an energetically low-lying triplet state. It emerges from the metal-metal contacts in the dimer. The biradical character of the dimer decreases in the order E = Al ≫ Ga > In. The carbene analogue of In forms upon dimerization of only weak coordinative metal-metal interactions.

Structural, optical and electrical properties of CuIn 5S 8 thin films grown by thermal evaporation method

Stoichiometric compound of copper indium sulfur (CuIn 5S 8) was synthesized by direct reaction of high purity elemental copper, indium and sulfur in an evacuated quartz tube. The phase structure of the synthesized material revealed the cubic spinel structure. The lattice parameter (a) of single crystals was calculated to be 10.667 Å. Thin films of CuIn 5S 8 were deposited onto glass substrates under the pressure of 10 −6 Torr using thermal evaporation technique. CuIn 5S 8 thin films were then thermally annealed in air from 100 to 300 °C for 2 h. The effects of thermal annealing on their physico-chemical properties were investigated using X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), optical transmission and hot probe method. XRD studies of CuIn 5S 8 thin films showed that as-deposited films were amorphous in nature and transformed into polycrystalline spinel structure with strong preferred orientation along the (3 1 1) plane after the annealing at 200 °C. The composition is greatly affected by thermal treatment. From the optical transmission and reflection, an important absorption coefficient exceeds 10 4 cm −1 was found. As increasing the annealing temperature, the optical energy band gap decreases from 1.83 eV for the as-deposited films to 1.43 eV for the annealed films at 300 °C. It was found that CuIn 5S 8 thin film is an n-type semiconductor at 300 °C.

Effect of intentional Na-incorporation on the structural, optical and electrical properties of CuInS2:Na thin films for solar energy conversion

Na-doped CuInS2 material is obtained by the incorporation of the sodium of an atomic percentage in amounts of 0, 0.1, 0.5, 1, 2 and 3% with a stoechiometric mixture of the elements copper, indium and sulfur taken in the stoechiometric proportions. We have investigated in this work the effect of intentional Na-incorporation on the structural, optical and electrical properties of CuInS2:Na-doped thin films grown by the single source thermal evaporation method. In the resulting Bridgman-grown ingots brittleness were increased with increased Na and measured hot point probe changed sign from p- to n-type in stoechiometric ingots above 0.5at.%. The samples having a low Na atomic percentage exhibit better crystallinity that shows the effect of the sodium for the larger percentage to degrade the crystallinity of layers (atomic percentage greater than 2at.%). The film conductivity was strongly affected by Na-doping, which increased from 10−6 to 10−3S/cm by increasing [Na]/[CuInS2] ratio from 0.1 to 3at.%. Indeed for an atomic percentage Na of 1% we obtained the biggest thickness (1μm) corresponds to the lowest refractive index value (2.08).

A comparative study of the properties of thermally evaporated CuIn 2n + 1 S 3n + 2 (n = 0, 1, 2 and 3) thin films

CuInS 2, CuIn 3S 5, CuIn 5S 8 and CuIn 7S 11 compounds were synthesized by the horizontal Bridgman method using high-purity copper, indium and sulphur elements. Crushed powders of these ingots were used as raw materials for the vacuum thermal evaporation. So, CuIn 2n + 1 S 3n + 2 (n = 0, 1, 2, and 3) thin films were deposited by single source vacuum thermal evaporation onto glass substrates heated at 150 °C. The structural, compositional, morphological, electrical and optical properties of the deposited films were studied using X-ray diffraction (XRD), energy dispersive X-ray, atomic force microscopy and optical measurement techniques. XRD results revealed that all the films are polycrystalline. However, CuInS 2 and CuIn 3S 5 films had a chalcopyrite structure with preferred orientation along 112 while CuIn 5S 8 and CuIn 7S 11 films exhibit a spinel structure with preferred orientation along 311. The absorption coefficients of the all CuIn 2n + 1 S 3n + 2 films are in the range of 10 −4 and 10 −5 cm −1. The direct optical band gaps of CuIn 2n + 1 S 3n + 2 layers are found to be 1.56, 1.78, 1.75 and 1.30 eV for n = 0, 1, 2, and 3, respectively. CuIn 3S 5 and CuIn 5S 8 films are p type with electrical resistivities of 4 and 12 Ω cm whereas CuInS 2 and CuIn 7S 11 are highly compensated with resistivities of 1470 and 1176 Ω cm, respectively.

Chemical vapour deposition of In2O3 thin films from a tris-guanidinate indium precursor

A new homoleptic sublimable indium(III) guanidinate, (In[(N(i)Pr)(2)CNMe(2)](3) (1), was synthesized from a facile high-yield procedure. Compound 1 crystallized is a P1 space group; a = 10.5989(14) Å, b = 11.0030(15) Å, c = 16.273(2) Å, α = 91.190(2)°, β = 96.561(2)°, γ = 115.555(2)°; R = 3.50%. Thermogravimetric analysis showed 1 to produce elemental indium as a residual mass. Thermolysis in a sealed NMR tube showed carbodiimide and protonated dimethyl amine by (1)H NMR. Chemical vapour deposition experiments above 275 °C with air as the reactant gas showed 1 to readily deposit cubic indium oxide with good transparency.

ChemInform Abstract: Indium Flux‐Growth of Eu2AuGe3: A New Germanide with an AlB2 Superstructure.

AbstractLarge single crystals of Eu2AuGe3 are prepared in high yield from the elements in liquid indium (1000 °C, 5 h).

Correlations between hardness and atomic bond parameters of pure metals and semi-metals after processing by high-pressure torsion

High-purity elements (magnesium, aluminum, silicon, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, germanium, zirconium, niobium, molybdenum, palladium, silver, indium, tin, tellurium, neodymium, hafnium, tantalum, tungsten, rhenium, platinum, gold and lead) were processed by high-pressure torsion and subsequently evaluated by Vickers microhardness measurements. The hardness at the steady state was expressed as a unique function of atomic bond energy, specific heat capacity, specific latent heat of fusion, linear thermal expansion coefficient and activation energy for self-diffusion.

Indium Flux-Growth of Eu2AuGe3: A New Germanide with an AlB2 Superstructure

The germanide Eu(2)AuGe(3) was obtained as large single crystals in high yield from a reaction of the elements in liquid indium. At room temperature Eu(2)AuGe(3) crystallizes with the Ca(2)AgSi(3) type, space group Fmmm, an ordered variant of the AlB(2) type: a = 857.7(4), b = 1485.5(10), c = 900.2(4) pm. The gold and germanium atoms build up slightly distorted graphite-like layers which consist of Ge(6) and Au(2)Ge(4) hexagons, leading to two different hexagonal-prismatic coordination environments for the europium atoms. Magnetic susceptibility data showed Curie-Weiss law behavior above 50 K and antiferromagnetic ordering at 11 K. The experimentally measured magnetic moment indicates divalent europium. The compound exhibits a distinct magnetic anisotropy based on single crystal measurements and at 5 K it shows a metamagnetic transition at ∼10 kOe. Electrical conductivity measurements show metallic behavior. The structural transition at 130 K observed in the single crystal data was very well supported by the conductivity measurements. (151)Eu Mössbauer spectroscopic data show an isomer shift of -11.24 mm/s at 77 K, supporting the divalent character of europium. In the magnetically ordered regime one observes superposition of two signals with hyperfine fields of 26.0 (89%) and 3.5 (11%) T, respectively, indicating differently ordered domains.

Study of the I– V characteristics of SnO 2:F/AgInS 2 (p)/Al Schottky diodes

AgInS 2 sprayed thin films have been deposited on glass SnO 2:F substrates using an aqueous solution which contains silver acetate (AgCH 3CO 2), thiourea (SC(NH 2) 2) and indium chloride (InCl 3) as precursors. The depositions were carried out at the substrate temperature of 420 °C. The concentration ratio in the spray solution of indium and silver elements x = [Ag +]/[In 3+] was equal to 1.3 whereas y = [S 2−]/[In 3+] was varied between 5 and 7. The current–voltage study of SnO 2:F/AgInS 2/Al Shottky diodes as a function of y composition has been carried out. A rectifier effect has been shown and the transport process is mainly governed by the generation-recombination and tunneling effects.

Extraction of copper from acidic leach solution with Acorga M5640 using a pulsed sieve plate column

The extraction of copper from acidic leach solution with the aldoxime Acorga M5640 using a pulsed sieve plate column has been investigated. The pregnant leach solution was produced through pressure leaching of an industrial sphalerite concentrate that contained zinc, iron, copper, indium and other minor elements. Bench scale studies on solvent extraction have been carried out for selecting the composition of the organic phase and the pH of the leach solution to perform the separation of copper. An organic phase with 10% (v/v) Acorga M5640 and 2.5% (v/v) isotridecanol was chosen to test the hydrodynamic and mass transfer performance of the extraction column. The results of the pilot plant experiments demonstrated the feasibility of operating the extraction of copper from the aqueous solution using a pulsed sieve plate column.

Structural studies of mechano-chemically synthesized CuIn1−xGaxSe2 nanoparticles

Abstract CuInGaSe 2 is a I–III–VI 2 semiconducting material of tetragonal chalcopyrite structure. It is a very prominent absorber layer for photovoltaic devices. Particle-based coating process for CIGS is considered to be promising technique with relatively simple procedures and low initial investment. In the present work CIGS nanoparticle precursors suitable for screen-printing ink has been prepared by ball milling. High purity elemental copper granules, selenium and indium powders and fine chips of gallium were used as starting materials. First the ball milling was carried out for CuIn 1− x Ga x Se 2 ( x = 0.5) with (i) 10 ml of ethyl alcohol (ii) 5 ml of tetra ethylene glycol (wet) and (iii) 1 ml of ethylene diamine (semi-dry) for a milling time of 3 h and the results are not stoichiometric. In order to obtain an improved stoichiometric composition dry ball milling of elemental sources for three different compositions of CuIn 1− x Ga x Se 2 ( x = 0.25, 0.5 and 0.75) has been carried out. X-ray diffraction analysis revealed the presence of (1 1 2), (2 2 0)/(2 0 4), (3 1 2)/(1 1 6), (4 0 0) and (3 3 2) reflections for all the milled powders. These reflections correspond to chalcopyrite structure of CIGS. Shift in peaks towards higher value of 2 θ is observed with the increase in Ga composition. Average grain size calculated by Scherrer's formula is found to be around 13 nm for the dry samples milled for 1.5 h and 7–8 nm for the samples wet milled for 3 h. Lattice constants ‘ a ’ and ‘ c ’ are found to decrease with the increase in concentration of Gallium. FESEM analysis revealed a strong agglomeration of the particles and the particle size varied from 11 to 30 nm for the dry-milled samples. Composition of milled powders has been studied by energy dispersive X-ray analysis. TEM analysis revealed the presence of nanocrystalline particles and SAED pattern corresponds to (1 1 2), (2 2 0)/(2 0 4), (5 1 2)/(4 1 7) and (6 2 0)/(6 0 4) diffraction peaks of CIGS. From the HRTEM analysis the d -spacing values were evaluated and found to be 1.06, 3.33, 2.03 and 0.906 A corresponding to the diffraction pattern. Also the planes corresponding to the nanoparticles have been simulated and matched with the HRTEM pattern. Raman spectra show the intense peak at 168–172 cm −1 , which corresponds to the chalcopyrite structure.

Characterization of (In 1− xAl x) 2S 3 thin films grown by co-evaporation

In this paper, it is shown that (In 1− x Al x ) 2S 3 thin films can be grown through the co-evaporation of elemental indium, aluminum and sulfur. It is nevertheless observed that the introduction of aluminum within the indium sulfide thin films hinders the crystallites size and even yields almost amorphous films when x is 0.2. The investigations of the optical properties of the films reveal that contrary to what could be expected, the band gap increase is low; the highest values measured do not exceed 2.2 eV. However, as suggested by X-ray photoelectron spectroscopy measurements, such widening most probably affects the lower conduction band states.

Structure and temperature dependence of conduction mechanisms in hot wall deposited CuInSe 2 thin films and effect of back contact layer in CuInSe 2 based solar cells

Copper indium diselenide (CuInSe 2) was prepared by direct reaction of high purity elemental Copper, Indium and Selenium. CuInSe 2 thin films were prepared on well-cleaned glass substrates by a hot wall deposition technique. The X-ray diffraction studies revealed that all the deposited films are poly crystalline in nature, single phase and exhibit chalcopyrite structure. The crystallites were found to have a preferred orientation along the (112) direction. Structural parameters of CuInSe 2 thin films coated with higher substrate temperatures were also studied. As the substrate temperature increases the grain size increases. The resistivity is found to decrease with increase in temperature. Two types of conduction mechanisms are present in the hot wall deposited CuInSe 2 films. In the temperature region below 215 K the conduction is due to a variable range hopping mechanism and in the temperature region above 215 K the conduction is due to a thermally activated process. It is observed that the solar cell with molybdenum as back contact has low series resistance ( R s), high shunt resistance ( R sh) and large fill factor (FF) when compared with CuInSe 2 based solar cells with other back contact material layers.

Comparative study of structural and morphological properties of CuIn 3S 5 and CuIn 7S 11 materials

CuIn 3S 5 and CuIn 7S 11 powders were prepared by solid-state reaction method using high-purity elemental copper, indium and sulphur. The films prepared from CuIn 3S 5 and CuIn 7S 11 powders were grown by thermal evaporation under vacuum (10 −6 Torr) on glass substrates at different substrate temperature Ts varying from room temperature to 200 °C. The powders and thin films were characterized for their structural properties by using X-ray diffraction (XRD) and energy dispersive X-ray (EDX). Both powders were polycrystalline with chalcopyrite and spinel structure, respectively. From the XRD data, we calculated the lattice parameters of the structure for the compounds. For CuIn 3S 5 powder, we also calculated the cation–anion bond lengths. The effect of substrate temperature Ts on the structural properties of the films, such as crystal phase, preferred orientation and crystallinity was investigated. Indeed, X-ray diffraction analysis revealed that the films deposited at a room temperature (30 °C) are amorphous in nature while those deposited on heated were polycrystalline with a preferred orientation along (1 1 2) of the chalcopyrite phase and (3 1 1) of the spinel phase for CuIn 3S 5 and CuIn 7S 11 films prepared from powders, respectively. The morphology of the films was determined by atomic force microscopy AFM. The surface roughness and the grain size of the films increase on increasing the substrate temperature.

Synthesis, elaboration and characterization of the new material CuIn3S5 thin films

CuIn3S5 compound was prepared by direct reaction of high-purity elemental copper, indium and sulphur. CuIn3S5 thin films were prepared from powder by thermal evaporation under vacuum (10−6 mbar) onto glass substrates. The glass substrates were heated from 30 to 200 °C. The powder was characterized for their structural and compositional properties by using X-ray diffraction (XRD) and energy dispersive X-ray (EDAX). The XRD studies revealed that the powder exhibiting P-chalcopyrite structure. From the XRD data, we calculated the lattice parameters a and c. Then, the cation–anion bond lengths lAC and lBC are deduced. The films were characterized for their structural, compositional, morphological and optical properties by using XRD, EDAX, atomic force microscopy and optical measurement techniques (transmittance and reflectance). XRD analysis revealed that the films deposited at a room temperature (30 °C) are amorphous in nature, whereas those deposited on heated substrates (≥75 °C) were polycrystalline with a preferred orientation along (112) of the chalcopyrite phase. The surface morphological analysis revealed that the films grown at different substrate temperature had an average roughness between 1.1 and 4.8 nm. From the analysis of the transmission and reflection data, the values of direct and indirect band gap of the films were determined. We found that the optical band gap decreases when the substrate temperature increases.

Investigations on electron beam evaporated Cu(In 0.85Ga 0.15)Se 2 thin film solar cells

CIGS bulk with composition of CuIn 0.85Ga 0.15Se 2 was synthesized by direct reaction of elemental copper, indium, gallium and selenium. CIGS thin films were then deposited onto well-cleaned glass substrates using the prepared bulk alloy by electron beam deposition method. The structural properties of the deposited films were studied using X-ray diffraction technique. The as-deposited CIGS films were found to be amorphous. On annealing, the films crystallized with a tetragonal chalcopyrite structure. An intermediate Cu-rich phase precipitated at 200 °C and dissociated at higher annealing temperatures. Average grain size calculated from the XRD spectra indicated that the films had a nano-crystalline structure and was further corroborated by AFM analysis of the sample surface. The chemical constituents present in the deposited CIGS films were identified using energy dispersive X-ray analysis. CIGS based solar cells were then fabricated on molybdenum and ITO coated glass substrates and the efficiencies have been evaluated.