Indium and tellurium doping of CdS crystals in cadmium vapor and their luminescent properties

A technique is devised for vapor-phase doping of CdS in the quaternary system Cd-In-Te-S. CdS crystals are doped with In and Te via four-zone annealing in Cd and InTe vapors. The luminescence spectra of the CdSIn,Te[Cd] crystals (where [Cd] indicates annealing in cadmium vapor) are found to contain orange and red emission bands, in contrast to those of CdS[Cd] crystals, which are dominated by green emission. The CdSIn,Te[Cd] crystals are shown to be photosensitive. Sphalerite (metastable) CdS crystals doped with In and Te are prepared under far-from-equilibrium conditions. The bands in their luminescence spectra are shifted to longer wavelengths as compared to stable CdSIn,Te[Cd] crystals.Translated from Neorganicheskie Materialy, Vol. 40, No. 12, 2004, pp. 1415–1417.Original Russian Text Copyright © 2004 by Odin, Chukichev, Rubina     

Luminescent Properties of CdS Crystals Doped with Gallium and Tellurium in Cadmium Vapor

A technique is devised for vapor-phase doping CdS in the quaternary system Cd–Ga–Te–S. CdS crystals are doped with Ga and Te via four-zone annealing in a vapor phase containing Ga, Te, and Cd (the more volatile component of CdS). The luminescence spectra of the CdSGa,Te[Cd] crystals are found to contain orange and red emission bands, in contrast to those of CdS[Cd] crystals, which are dominated by green emission.     

Platelet-derived growth factor receptor expression after neural grafting in a rat model of Parkinson's disease

Platelet-derived growth factor (PDGF) has trophic effect on dopaminergic neurons in vitro. We have previously shown dynamic changes in the expression of PDGF in embryonic mesencephalic grafts and surrounding host striatal tissue following intracerebral transplantation in a rat model of Parkinson's disease. In this study the expression of the PDGF receptors was examined in the same model using immunohistochemistry. Most ventral mesencephalic (VM) cells from E13-E15 rat embryos possessed both PDGF alpha- and beta-receptors before implantation. Double immunofluorescence staining revealed that about 10% of the cells also expressed tyrosine hydroxylase (TH). The PDGF alpha-receptor was detectable in the graft up to 1 wk after transplantation but had disappeared at 3 wk. In the host tissue, scattered glial cells were positive for the alpha-receptor but the expression was unchanged following transplantation. The beta-receptor expression almost completely disappeared from the grafted tissue by 4 h following transplantation, and only a few cells of the host striatum showed immunoreactivity. However, after 3 wk beta-receptor positive cells were again detectable in the graft. These cells appeared to be endothelial cells as identified by an antibody against von Willebrand's factor. Our data suggest that PDGF might act locally on embryonic dopaminergic cells in an autocrine or juxtacrine manner before and shortly after transplantation, and on surrounding glial cells in a paracrine manner after transplantation. Furthermore, PDGF-BB might influence neovascularization in the graft.     

Luminescent properties of CdSe single crystals doped with antimony or bismuth

CdSe single crystals were doped with Bi and Sb from Sb₂Se₃ and Bi₂Se₃ vapors. The introduction of Sb and Bi was found to produce new luminescence centers. Both bismuth and antimony generate deep levels in the band gap of CdSe. The maxima in the photoconductivity spectra of Sb and Bi-doped CdSe are redshifted. Both doped and undoped CdSe crystals are shown to be photosensitive     

Detection of equipment aging and determination of the efficiency of a corrective measure

When too many failures occur on a given piece of equipment, the dependability engineer needs to decide whether these failures are attributable to poor initial design or if they are due to a phenomenon of aging. If aging is confirmed, the problem is then to determine the moment at which the process began and what corrective measure (generally, a modification in the design or in the preventive maintenance program) is the best suited to delay the occurrence of the failure. This measure will thus make it possible to extend the lifetime of the equipment.The method is based on the simple hypothesis of a model of step aging and on Bayesian techniques.The principal benefit of this method is the determination of the time at which aging begins (and the related uncertainties), the evolution in the failure rate of the component in its initial state and once modified, and the probability of success of the corrective measure. The IBTV software was developed to implement this methodology.     

Effects of iso-and heterovalent substitutions on the luminescent properties of CdS in the systems Zn, Cd ‖ S, Te and In(III), Cd ‖ S, Te

We have studied the luminescent properties of three CdS-based solid-solution series, resulting from isovalent anion substitution (CdS_1?x Te_x), isovalent cation and anion substitutions (Cd_1?x Zn_xS_1?x Te_x), and heterovalent cation substitution in combination with isovalent anion substitution (Cd_1?x In_2x/3S_1?x Te_x). The last two systems have been studied for the first time. The results demonstrate that red or near-IR lumiescence occurs in the three systems, but CdS crystals codoped with In and Te are more attractive because of the high impurity-related emission intensity at rather low In and Te concentrations.     

Effect of the Copper Content on the Kinetics of the Microwave Photoconductivity of CIGS Solid Solutions

Semiconductors - The kinetics of the photoresponse of microwave photoconductivity (9 GHz, TE101-type cavity) on excitation by laser light pulses with a wavelength of 337 nm and a duration of 8 ns...