Cadmium Telluride

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Andreas Wade - One of the best experts on this subject based on the ideXlab platform.

  • fate and transport evaluation of potential leaching risks from Cadmium Telluride photovoltaics
    Environmental Toxicology and Chemistry, 2012
    Co-Authors: Parikhit Sinha, Robert Balas, Lisa Krueger, Andreas Wade
    Abstract:

    yFirst Solar, Tempe, Arizona, USAzIris Environmental, Oakland, California, USA§First Solar GmbH, Berlin, Germany(Submitted 23 November 2011; Returned for Revision 17 January 2012; Accepted 8 March 2012)Abstract—Fate and transport analysis has been performed to evaluate potential exposures to Cadmium (Cd) from Cadmium Telluride(CdTe) photovoltaics (PV) for rainwater leaching from broken modules in a commercial building scenario. Leaching from brokenmodules is modeled using the worst-case scenario of total release of Cd, and residential screening levels are used to evaluate potentialhealth impacts to on-site workers and off-site residents. A rooftop installation was considered rather than a ground-mount installationbecause rainwater runoff isconcentrated viabuilding downspouts ina rooftop installation ratherthan being dispersed across large areasinaground-mountinstallation.FateandtransportofCdfromleachatetosoilaremodeledusingequilibriumsoil/soil-waterpartitioning.SubsequentmigrationtoambientairaswindblowndustisevaluatedwithascreeningGaussianplumedispersionmodel,andmigrationtogroundwaterisevaluatedwithadilution-attenuationfactorapproach.Exposurepointconcentrationsinsoil,air,andgroundwaterareoneto six orders of magnitude below conservative (residential soil, residential air, drinking water) human health screening levels in both aCaliforniaandsouthernGermany(Baden-Wu¨rttemberg)exposurescenario.PotentialexposurestoCdfromrainwaterleachingofbrokenmodules in a commercial building scenario are highly unlikely to pose a potential health risk to on-site workers or off-site residents.Environ. Toxicol. Chem. 2012;31:1670–1675. # 2012 SETACKeywords—Cadmium Telluride Leaching Risk assessment Fate and transport Cadmium Telluride photovoltaicsINTRODUCTION

Robert F. Hicks - One of the best experts on this subject based on the ideXlab platform.

  • The chemistry of the organometallic vapor-phase epitaxy of mercury Cadmium Telluride
    Proceedings of the IEEE, 1992
    Co-Authors: Robert F. Hicks
    Abstract:

    This review of the organometallic vapor-phase epitaxy (OMVPE) of mercury Cadmium Telluride examines the chemistry underlying film growth, film morphology, heteroepitaxy, doping, and reactor design. A key feature of the OMVPE of II-VI compounds, as distinguished from the OMVPE of III-V compounds, is that the intrinsic reaction kinetics control film growth. The rates of surface and gas-phase reactions determine the rate of deposition and the alloy composition. As a result, the quality of the material produced is very sensitive to the substrate temperature and the distribution of reactants in the gas above the substrate. Another crucial aspect of the growth chemistry is that Cadmium Telluride shows a strong tendency to grow in the 111(Te) orientation. This makes it difficult to establish layer-by-layer growth on the

  • Modeling of the coupled kinetics and transport in the organometallic vapor-phase epitaxy of Cadmium Telluride
    Journal of Crystal Growth, 1991
    Co-Authors: Anthony H. Mcdaniel, Robert F. Hicks
    Abstract:

    A catalytic reaction mechanism is proposed for the organometallic vapor-phase epitaxy of Cadmium Telluride. DimethylCadmium and diethyltellurium dissociatively adsorb onto exposed metal atoms on the Cadmium Telluride surface. The sticking probability is given by S = 1.5×10-4(1−θR), where θR is the methyl and ethyl coverage. Subsequently, methyl and ethyl radicals desorb at a rate given by rd = 1.5×109exp(-25 [kcal/mol]RT)θR(s-1). This mechanism is consistent with surface science studies of the adso rption and decomposition of organometallic molecules on semiconductor surfaces. A boundary-layer model incorporating the catalytic reaction is used to simulate the kinetics of Cadmium Telluride deposition in a horizontal, cold-wall reactor. The simulations show the same dependence of the growth rate on temperature as was observed by I.B. Bhat et al. [J. Electrochem. Soc. 134 (1987) 195] on sapphire substrates. The growth rate increases exponentially with temperature below 350°C, but remains constant above 400°C. At low temperatures, the reaction is controlled by the desorption of alkyl radicals. At high temperatures, the reaction is mainly controlled by the adsorption of organometallic molecules. The growth rate changes when different substrates are used in the experiments. This suggests that the kinetics of alkyl radical desorption are influenced by the Cadmium Telluride surface structure.

Parikhit Sinha - One of the best experts on this subject based on the ideXlab platform.

  • fate and transport evaluation of potential leaching risks from Cadmium Telluride photovoltaics
    Environmental Toxicology and Chemistry, 2012
    Co-Authors: Parikhit Sinha, Robert Balas, Lisa Krueger, Andreas Wade
    Abstract:

    yFirst Solar, Tempe, Arizona, USAzIris Environmental, Oakland, California, USA§First Solar GmbH, Berlin, Germany(Submitted 23 November 2011; Returned for Revision 17 January 2012; Accepted 8 March 2012)Abstract—Fate and transport analysis has been performed to evaluate potential exposures to Cadmium (Cd) from Cadmium Telluride(CdTe) photovoltaics (PV) for rainwater leaching from broken modules in a commercial building scenario. Leaching from brokenmodules is modeled using the worst-case scenario of total release of Cd, and residential screening levels are used to evaluate potentialhealth impacts to on-site workers and off-site residents. A rooftop installation was considered rather than a ground-mount installationbecause rainwater runoff isconcentrated viabuilding downspouts ina rooftop installation ratherthan being dispersed across large areasinaground-mountinstallation.FateandtransportofCdfromleachatetosoilaremodeledusingequilibriumsoil/soil-waterpartitioning.SubsequentmigrationtoambientairaswindblowndustisevaluatedwithascreeningGaussianplumedispersionmodel,andmigrationtogroundwaterisevaluatedwithadilution-attenuationfactorapproach.Exposurepointconcentrationsinsoil,air,andgroundwaterareoneto six orders of magnitude below conservative (residential soil, residential air, drinking water) human health screening levels in both aCaliforniaandsouthernGermany(Baden-Wu¨rttemberg)exposurescenario.PotentialexposurestoCdfromrainwaterleachingofbrokenmodules in a commercial building scenario are highly unlikely to pose a potential health risk to on-site workers or off-site residents.Environ. Toxicol. Chem. 2012;31:1670–1675. # 2012 SETACKeywords—Cadmium Telluride Leaching Risk assessment Fate and transport Cadmium Telluride photovoltaicsINTRODUCTION

W. R. Wilcox - One of the best experts on this subject based on the ideXlab platform.

  • Floating zone melting of Cadmium Telluride
    1992
    Co-Authors: Wen-ming Chang, L. L. Regel, W. R. Wilcox
    Abstract:

    To produce superior crystals of Cadmium Telluride, floating zone melting in space has been proposed. Techniques required for floating zone melting of Cadmium Telluride are being developed. We have successfully float-zoned Cadmium Telluride on earth using square rods. A resistance heater was constructed for forming the molten zone. Evaporation of the molten zone was controlled by adding excess Cadmium to the growth ampoule combined with heating of the entire ampoule. An effective method to hold the feed rod was developed. Slow rotation of the growth ampoule was proven experimentally to be necessary to achieve a complete symmetric molten zone. Most of the resultant cylindrical rods were single crystals with twins. Still needed is a suitable automatic method to control the zone length. We tried a fiber optical technique to control the zone length, but experiments showed that application of this technique to automate zone length control is unlikely to be successful.

  • Surface tension and contact angles of molten Cadmium Telluride
    International Journal of Thermophysics, 1990
    Co-Authors: Raghuraman Balasubramanian, W. R. Wilcox
    Abstract:

    The surface tension and contact angle of molten Cadmium Telluride (CdTe) were measured as a function of temperature by the sessile drop technique. A FORTRAN code was developed to calculate the surface tension of sessile drops, with the contact angle ranging from 0 to 180�. The wetting of Cadmium Telluride melt was studied on different surfaces. The surface tension of Cadmium Telluride was about 160 � 5 dynes � cm-1[1.6N � m-1.] at the melting point of 1093�C. The contact angle of CdTe melt was about 65� on a quartz optical flat, 75� on commercial fused quartz, and 125� on boron nitride coated quartz.

Robert Balas - One of the best experts on this subject based on the ideXlab platform.

  • fate and transport evaluation of potential leaching risks from Cadmium Telluride photovoltaics
    Environmental Toxicology and Chemistry, 2012
    Co-Authors: Parikhit Sinha, Robert Balas, Lisa Krueger, Andreas Wade
    Abstract:

    yFirst Solar, Tempe, Arizona, USAzIris Environmental, Oakland, California, USA§First Solar GmbH, Berlin, Germany(Submitted 23 November 2011; Returned for Revision 17 January 2012; Accepted 8 March 2012)Abstract—Fate and transport analysis has been performed to evaluate potential exposures to Cadmium (Cd) from Cadmium Telluride(CdTe) photovoltaics (PV) for rainwater leaching from broken modules in a commercial building scenario. Leaching from brokenmodules is modeled using the worst-case scenario of total release of Cd, and residential screening levels are used to evaluate potentialhealth impacts to on-site workers and off-site residents. A rooftop installation was considered rather than a ground-mount installationbecause rainwater runoff isconcentrated viabuilding downspouts ina rooftop installation ratherthan being dispersed across large areasinaground-mountinstallation.FateandtransportofCdfromleachatetosoilaremodeledusingequilibriumsoil/soil-waterpartitioning.SubsequentmigrationtoambientairaswindblowndustisevaluatedwithascreeningGaussianplumedispersionmodel,andmigrationtogroundwaterisevaluatedwithadilution-attenuationfactorapproach.Exposurepointconcentrationsinsoil,air,andgroundwaterareoneto six orders of magnitude below conservative (residential soil, residential air, drinking water) human health screening levels in both aCaliforniaandsouthernGermany(Baden-Wu¨rttemberg)exposurescenario.PotentialexposurestoCdfromrainwaterleachingofbrokenmodules in a commercial building scenario are highly unlikely to pose a potential health risk to on-site workers or off-site residents.Environ. Toxicol. Chem. 2012;31:1670–1675. # 2012 SETACKeywords—Cadmium Telluride Leaching Risk assessment Fate and transport Cadmium Telluride photovoltaicsINTRODUCTION