Deposition of cadmium sulfide films by decomposition of thiourea in basic solutions

Rieke, Peter C.; Bentjen, Susan B.

doi:10.1021/cm00025a012

Cited by 129 publications

(96 citation statements)

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“…The binding energy of the Cd 3d 3/2 peak was 411.7 eV, which agrees with the 6.74 eV energy splitting between Cd 3d 5/2 and Cd 3d 3/2 states [40]. Both values of binding energy for S 2p and Cd 3d peaks observed in all three films agree well with previously reported data on single crystal and thin film CdS [41,42]. It is worth noting that the ratio of S 2p 3/2 signal intensity to that of the Cd 3d 5 figure 15, both undoped and Al-doped films are smooth, continuous and uniform with some coverage by scattered crystallite overgrowth that appear to have the same density for both films.…”

Section: Hexagonal Cdssupporting

confidence: 90%

Investigation of aluminium and indiumin situdoping of chemical bath deposited CdS thin films

Khallaf

Chai

Lupan

et al. 2008

J. Phys. D: Appl. Phys.

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Aluminum and indium in situ doping of CdS using chemical bath deposition (CBD) is investigated. The effects of Al and In-doping on optical properties as well as on electrical properties, crystal structure, chemistry and morphology of CdS films are studied. Al doping of CdS using CBD is shown to be successful where a resistivity as low as 4.6 × 10 −2 cm and a carrier density as high as 1.1 × 10 19 cm −3 were achieved. The bandgap of Al-doped films decreases to a minimum of 2.26 eV, then slightly increases and finally saturates at 2.30 eV as the [Al]/[Cd] ratio in solution increases from 0.018 to 0.18. X-ray diffraction studies showed Al 3+ ions entering the lattice substitutionally at low concentration and interstitially at high concentration. Phase transition, due to annealing, and induced lattice damage, due to doping, were detected by micro-Raman spectroscopy. Film stoichiometry was found to be sensitive to Al concentration, while film morphology was unaffected by Al doping. Indium doping using CBD, however, was found to be highly unlikely due to the low solubility of indium sulfide. Instead, the formation of InS/In 2 S 3 dominated the deposition process over CdS.

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Section: Hexagonal Cdssupporting

confidence: 90%

Investigation of aluminium and indiumin situdoping of chemical bath deposited CdS thin films

Khallaf

Chai

Lupan

et al. 2008

J. Phys. D: Appl. Phys.

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“…Factors influencing the formation of CSCS: Thiourea (TU), a sulfur source which has been commonly used for the deposition of metal-sulfide films [28,29] or other nanostructures in basic solutions, [30][31][32] remains stable up to 180 8C in reaction systems without metal cations. However, this compound decomposes at relatively low temperatures in an aqueous solution in the presence of many metal cations including Cd 2 + .…”

Section: Resultsmentioning

confidence: 99%

Controlled Synthesis, Growth Mechanism, and Properties of Monodisperse CdS Colloidal Spheres

et al. 2007

Chemistry A European J

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Highly monodisperse submicrometer CdS colloidal spheres (CSCS) with a controllable and tunable size (between 80 and 500 nm) have been synthesized through a facile solvothermal technique. Owing to the controllability of the reaction process, the growth mechanism of the colloidal spheres has been elucidated in detail. The whole growth process can be summarized as homogenous and slow nucleation of nanocrystals, formation of "cores" through 3D-oriented attachment of nanocrystals, and further surface-induced growth to monodisperse colloidal spheres through in situ formation and random attachment of additional nanocrystals. It has been demonstrated that the obtained CSCS colloidal particles are able to be assembled into films which show characteristic stop band gaps of photonic crystals. By using the CSCS as a template, Ag2S, Bi2S3, Cu2S, HgS, and Sb2S3 colloidal spheres, which are difficult to obtain directly, have also been prepared successfully through ion exchange.

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“…In the absence of catalytic metals, for example when all the cadmium is precipitated, thiourea decomposes in alkaline solutions to produce sul®de ions and also other products, such as urea, ammonia and cyanate. 16 …”

Section: Qualitative Descriptionmentioning

confidence: 99%

“…The residual cadmium concentration in the solution depends, as seen above, principally on residual ammonia and pH for a given excess of Tu. The calculated conversion fraction of Tu at equilibrium versus pH of the solution is shown in Figure 8 for 2Á74 14Á38 0Á25 ± 0Á19 0Á81 0Á84 ± 0Á85 17Á65 2Á91 14Á19 0Á12 0Á81 0Á82 17Á62 2Á95 14Á63 0Á15 0Á83 0Á83 17Á45 2Á98 14Á49 0Á18 0Á83 0Á83 17Á58 3Á01 14Á55 0Á17 0Á83 0Á83 17Á62 3Á16 14Á59 0Á27 0Á83 0Á85 *Equation (16) the conditions used in this study ([Cd] T 0Á011 mol/l and [Tu] T 0Á014 mol/l). Experimental data are given in Table IV.…”

Section: Cadmium Con®nementmentioning

confidence: 99%

“…However, thiourea is not stable and decomposes in acidic media to produce several compounds (sulfur, urea, ammonia, cyanate) which themselves decompose, ®nally to ammonium carbonate. 16,26±28 A very light further treatment is perhaps necessary before discharge, at least pH adjustment. S spectrophotometric method; P polarographic determination; pH initial after CBD, before stripping…”

Section: Cadmium Con®nementmentioning

confidence: 99%

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Ammonia recycling and cadmium confinement in chemical bath deposition of CdS thin layers

Malinowska

Rakib

Durand

2001

Progress in Photovoltaics

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Cadmium sul®de thin layers in polycrystalline solar cells are produced by chemical bath deposition (CBD). This process produces wastes containing ammonia and cadmium. These two chemicals must be recovered, and if possible recycled, from an environmental and economic point of view. A process has been implemented in order to recover ammonia and to con®ne cadmium. A new closed reactor has been designed and fabricated in order to trap ammonia vaporized during the deposition step. Ammonia is absorbed from the exhaust gas from the CBD reactor. The wastes are treated in an ex situ process which enables recovery of the major part of the large amounts of ammonia used in the process. Concentrated solutions of pure ammonia are obtained (more than 10 mol/l). In connection with this operation, all of the cadmium, except a very small amount, is precipitated, mainly as cadmium sul®de, owing to decomposition of the thiourea introduced in excess. Micro®ltration with a glass-®ber ®lter of about 0Á7 lm cut-off produces a ®ltrate of very low cadmium concentration (< 10 lg/l). Optimization of both pH and residual ammonia concentration should make it possible to lower this residual cadmium concentration. This ef¯uent is the only waste product of the process. The ®ltration cake containing cadmium compounds may be stored in specialized land®lls after standard treatment or, better, treated to recover and recycle the metal without generation of any other harmful ef¯uent.

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Deposition of cadmium sulfide films by decomposition of thiourea in basic solutions

Cited by 129 publications

References 0 publications

Investigation of aluminium and indiumin situdoping of chemical bath deposited CdS thin films

Investigation of aluminium and indiumin situdoping of chemical bath deposited CdS thin films

Controlled Synthesis, Growth Mechanism, and Properties of Monodisperse CdS Colloidal Spheres

Ammonia recycling and cadmium confinement in chemical bath deposition of CdS thin layers

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