Formation reactions of chalcopyrite compounds and the role of sodium doping (original) (raw)
Related papers
Structure modifications in chalcopyrite semiconductors
2000
The microstructure of epitaxial CuInS 2 , CuGaSe 2 and polycrystalline CuInS 2 ®lms was studied by transmission electron microscopy. We found that the vapour-phase epitaxy of CuInS 2 below the transition temperature T c results in ®lms with chalcopyrite and CuAu-like structures. The formation of CuAu-like ordered phases within the ®lms is independent of the substrate orientation, whereas the amount of CuAu-like ordered Cu and In atoms can be in¯uenced by the substrate orientation. The co-existence of chalcopyrite and CuAu-like ordering of the metal atoms was also found in polycrystalline CuInS 2 ®lms prepared by sulphurization of Cu/In metal precursor at a temperature below T c . In contrast, vapour-phase epitaxy of CuGaSe 2 below T c provides only ®lms with the chalcopyrite structure. The experimental ®nding is in good agreement with the results of ®rst-principle band-structure calculations. q 2000 Elsevier Science S.A. All rights reserved.
Synthesis of Chalcopyrite Semiconductors and Their Solid Solutions by Microwave Irradiation
Chemistry of Materials, 1995
Chalcopyrite semiconductor compounds, MIMII'E2 (MI = Cu, Ag; M'II = Al, Ga, In; E = S, Se, Te), have been prepared by microwave irradiation of appropriate mixtures of the pure elements in a domestic microwave oven and characterized by X-ray diffraction (XRD) and energy-dispersive X-ray (EDX) analysis. Alloys of the type CuInSxSe2, and CuInSexTe2, (0 < x < 2 ) analyzed by XRD show that solid solutions are formed and there is no site preference for one chalcogenide over another. The crystallographic lattice parameters a and c were found to increase linearly rather than parabolically with increasing amounts of selenium.
A Review of Single Source Precursors for the Deposition of Ternary Chalcopyrite Materials
2002
The development of thin-film solar cells on flexible, lightweight, space-qualified durable substrates (i.e. Kapton) provides an attractive solution to fabricating solar arrays with high specific power, (W/kg). The syntheses and thermal modulation of ternary single source precursors, based on the [{LR}2Cu(SR')2In(SR')2] architecture in good yields are described. Thermogravimetric analyses (TGA) and Low temperature Differential Scanning Caloriometry, (DSC) demonstrate that controlled manipulation of the steric and electronic properties of either the group five-donor and/or chalcogenide moiety permits directed adjustment of the thermal stability and physical properties of the precursors. TGA-Evolved Gas Analysis, confirms that single precursors decompose by the initial extrusion of the sulphide moiety, followed by the loss of the neutral donor group, (L) to release the ternary chalcopyrite matrix. X-ray diffraction studies, EDS and SEM on the non-volatile pyrolized material dem...
Inorganica Chimica Acta, 2018
Complexes of the type (PPh 3) 2 M(μ-SEt) 2 E(SEt) 2 (M = Cu, Ag; E = Al, Ga, In) are effective and versatile molecular precursors for bimetallic and mixed MES 2 chalcopyrite nanomaterials. In solution at room temperature, these compounds exhibit spectroscopic characteristics inconsistent with their cyclic solid state structures, and variable temperature NMR investigations in this report show that this discrepancy is a result of rapid exchange of thiolate groups between bridging and terminal positions. These experiments show that the exchange is unimolecular and does not involve phosphine dissociation or free thiol. Exchange rates are not strongly affected by thiolate electronic properties or the identity of E, but are significantly slower for more sterically demanding phosphine and thiolate ligands. Data are consistent with a simple turnstyle exchange mechanism involving dissociation of one bridging thiolate ligand from M, although crossover studies suggest that full ionic dissociation (into [(PPh 3) 2 M][E(SEt) 4 ]) is also facile, and that dissociation into neutral fragments (PPh 3) 2 MSEt + E (SEt) 3 may proceed at higher temperatures. Additional investigation of the solution state thermolyses of the same complexes demonstrates that the processes above do not correlate to their decomposition behavior, as thermal sensitivity is most strongly effected by thiolate electronic properties, and likely depends most strongly on cleavage of CeS bonds.
Preparation and characterization of chalcopyrite compound for thin film solar cells
Alexandria Engineering Journal, 2011
CulnS 2 thin films were electrodeposited onto indium tin oxide substrate by the electrodeposition technique. Cyclic voltammetry and chronoamperometry were carried out to determine the optimum pH and the amount of sodium thiosulfate for electroplating CuInS 2 compound. The composition, crystallinity and optical properties of the compounds synthesized were studied by energy dispersive X-ray (EDX), (SEM), X-ray diffraction and UV-Visible spectra. It was found that the increasing pH shifts the electrodepositions voltage toward more negative and lowers the deposition current. Increasing the amount of sodium thiosulfate also decreases the deposition current but it has no effect on the deposition potential. It was concluded that CuInS 2 with atomic stoichiometric ratio was prepared at pH equals 1 and 150 ml of 0.1 M sodium thiosulfate, 5 ml of 0.1 M indium chloride and 5 ml of 0.1 M cupper acetate. The energy gaps were calculated to be 1.6, 1.7 and 1.75 eV for CuInS 2 prepared at 1, 1.5 and 2 of pH, respectively. It was indicated that the amount of the sodium thiosulfate has a slight effect on the energy gap.
Solar Energy Materials and Solar Cells, 2010
Chalcopyrite Nanostructures Solar cells Nanostructured chalcopyrite compounds have recently been proposed as absorber materials for advanced photovoltaic devices. We have used photoreñectance (PR) to evalúate the impact of interdiffusion phenomena and the presence of native defects on the optoelectronic properties of such materials. Two model material systems have been analyzed: (i) thin layers of CuGaSe 2 (£ g =1.7 eV) and CuInSe 2 (1.0 eV) in a wide/low/wide bandgap stack that have been grown onto GaAs(0 0 1) substrates by metalorganic chemical vapor deposition (MOCVD); and (ii) thin In 2 S 3 samples (£ g =2.0 eV) containing small amounts of Cu that have been grown by co-evaporation (PVD) intending to form Cu x In y S z (£ g~1 .5 eV) nanoclusters into the In 2 S 3 matrix. The results have been analyzed according to the third-derivative functional form (TDFF). The valence band structure of selenide reference samples could be resolved and uneven interdiffusion of Ga and In in the layer stack could be inferred from the shift of PR-signatures. Hints of electronic confinement associated to the transitions at the low-gap región have been found in the selenide layer stack. Regarding the sulphide system, In 2 S 3 is characterized by the presence of native deep states, as revealed by PR. The defect structure of the compound undergoes changes when incorporating Cu and no conclusive result about the presence of ternary clusters of a distinct phase could be drawn. Interdiffusion phenomena and the presence of native defects in chalcopyrites and related compounds will determine their potential use in advanced photovoltaic devices based on nanostructures. (D. Fuertes Marrón). energy range of zero density of states, as originally proposed by Luque and Martí . The device is completed with two emitters that selectively extract electrons and holes at either side of the absorber. In this way, three absorption onsets are expected at photon energies corresponding to transitions from the valence band to the intermedíate band, from the intermedíate to the conduction band, and from the valence to the conduction band, leading to an increase of the generated photocurrent. The proper use of the emitters and the isolation of the intermedíate band material from the contacts ensure that the expected voltage delivered by the device will be limited by the main gap of the material and not by any of the sub-bandgaps associated to the intermedíate band. The overall balance is an increased efficiency of energy conversión .
STRUCTURAL AND ELECTRONIC PROPERTIES OF CHALCOPYRITE SEMICONDUCTORS
This is to certify that the project thesis entitled " Structural and electronic properties of chalcopyrite semiconductor" being submitted by Bijayalaxmi Panda in partial fulfilment to the requirement of the one year project course (PH 592) of MSc Degree in physics of National Institute of Technology, Rourkela has been carried out under my supervision. The result incorporated in the thesis has been produced by using TB-LMTO codes.