Effects of Adsorption of Gaseous Ambients on the Photoluminescence Intensity of a Powdered CdS:Te Phosphor

Patel, Manish; Pu, CunJiang J.; Sharpe, Lee R.

doi:10.1021/la00006a029

Cited by 10 publications

(5 citation statements)

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“…3.2). Patel and co−work− ers [33] have reported that in powder phosphors of CdS:Te, the PL increases upon exposure to ammonia, which they at− tributed to the inter relationship between magnitude of the electric field in the near surface region and the PL intensity. Thus, it can be inferred that in the present system also, the increasing concentration of ammonia results in some sur− face effects; predominant in the nano crystalline material that subsequently produces changes in the PL intensities.…”

Section: Xrd Studiesmentioning

confidence: 99%

Photoconductivity and photoluminescence in chemically deposited films of CdSSe:CdCl2,Ho

Bhushan

Oudhia

2009

Opto-Electronics Review

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Results of the scanning electron microscopy (SEM), X-ray diffraction (XRD), optical absorption, photoconductivity (PC), and photoluminescence (PL) studies for the CdSSe:CdCl2,Ho films are presented in this paper. The SEM studies of different CdSSe films show a layered growth structure. A crystalline nature of the films is observed in the XRD studies. The regions with stacking fault were also observed in the X-ray diffractograms. The optical absorption spectra of these films show variations corresponding to the band gaps and the grain-sizes obtained under various deposition conditions and also with annealing. The effect of flux, impurities and annealing on the saturated photo to dark current ratio Ipc/Idc is observed in the PC rise and decay studies. The maximum value of Ipc/Idc ∼107 is obtained for the impurity doped annealed films. The PL emission spectra of CdSSe films show two emission peaks associated with the annihilation of free excitons and the transitions between shallow donor and deep acceptor states. In CdSSe:CdCl2,Ho films, two PL emission peaks are observed at 495 nm and 545 nm corresponding to the transitions 5S2→5I8 and 5F3→5I8, respectively, in Ho. The effect of pH on PL and grain size is also included in the present studies.

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Section: Xrd Studiesmentioning

confidence: 99%

Photoconductivity and photoluminescence in chemically deposited films of CdSSe:CdCl2,Ho

Bhushan

Oudhia

2009

Opto-Electronics Review

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“…Interest in semiconductor gas sensors has rapidly increased over the recent years because of their potential applications in environmental protection, medicine, industry, security etc [1]. Absorbed gases can modify some electrical and optical properties of semiconductors such as dark conductivity and photoconductivity [2], mobility-lifetime product and photoluminescence [3,4] by changing the concentration of electronic defects, introducing donors or acceptors, by alteration of the potential barrier height between crystalline grains or by surface band bending. Gas sensors based on semiconductor thin films have a higher sensitivity and shorter time response than bulk samples or thick films [5][6][7] due to their higher porosity.…”

Section: Introductionmentioning

confidence: 99%

Electrical properties of nanocrystalline CdSe thin films prepared by thermal vacuum evaporation

Aneva

Nesheva

Main

et al. 2008

Semicond. Sci. Technol.

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Thin films of CdSe with thicknesses of 50, 75 and 100 nm were prepared by physical vapour deposition using a 'one-step' or a 'step-by-step' deposition approach. The influence of the deposition conditions and film thickness on the microstructure and electrical properties has been explored by means of atomic force microscopy (AFM), dark conductivity, photoconductivity and thermally stimulated conductivity measurements. The AFM results have shown that smaller grains are formed in thinner films and that the size decrease is enhanced when the step-by-step deposition approach is used. A significant increase of the dark current activation energy with decreasing layer thickness has been registered and identified with a Fermi-level shift. A decrease of dark conductivity and photoconductivity has been observed with decreasing layer thickness which has been connected with both a size-induced increase of the interface defect density and appearance of new 'faster' recombination centres. The observed decrease is stronger in step-by step layers, in which the density of incorporated oxygen is higher. The oxygen creates new acceptor defects and causes band bending at grain boundaries. From the thermally stimulated conductivity data two kinds of defect states have been resolved situated at about 0.55 eV and 0.67 eV below the conduction band. A simultaneous fitting method has been applied to determine the main trap parameters.

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“…PL intensity increases with increasing concentration of NH 4 OH. This may be due to some surface effects like change in electric field intensity in the surface region, which produces higher emission due to increasing pH value [24]. In all the emission spectra studied, PL intensity was found to be maximum in the wavelength region 546-550nm (green region) which may be due to the 5 D 4 → 7 F 5 transition in Tb 3+ ions [16].…”

Section: Resultsmentioning

confidence: 86%

Photoconductivity and photoluminescence in chemically deposited (Cd‐Zn)S:CdCl₂,Tb films

Bhushan¹,

Pillai

2008

Cryst. Res. Technol.

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Results of SEM, EDX and XRD studies, Optical Absorption spectra, Photoconductivity (PC) rise and decay, PC excitation spectra and Photoluminescence (PL) emission spectra are presented for (Cd-Zn)S:CdCl 2 , Tb films prepared by chemical deposition method on glass substrates either at room temperature (RT) or at 60 ο C in a water bath (WB). SEM studies show ball type structure which is related to layered growth. EDX measurements show excess of Cd in such preparations along with the presence of Tb. XRD studies show prominent diffraction lines of CdS and ZnS along with lines of CdCl 2 and impurity. The values of strain (ε), grain size (D), and dislocation density (δ) are evaluated from XRD studies and the nature of crystallinity of the films are discussed. Optical Absorption spectra also show the presence of Tb in the lattice corresponding to the transition 7 F 6 (4f) of Tb 3+ ions. From results of optical absorption spectra, the band gaps are determined, whose values are quite similar to those obtained from PC excitation spectra. Sufficiently high photo current (I pc ) to dark current (I dc ) ratios with a maximum value of the order of 10 6 are observed. This high photosensitisation is related to increase in mobility and lifetime of carriers due to photo excitation. PL emission spectra consist of peaks due to transitions in Tb levels.

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Effects of Adsorption of Gaseous Ambients on the Photoluminescence Intensity of a Powdered CdS:Te Phosphor

Cited by 10 publications

References 1 publication

Photoconductivity and photoluminescence in chemically deposited films of CdSSe:CdCl2,Ho

Photoconductivity and photoluminescence in chemically deposited films of CdSSe:CdCl2,Ho

Electrical properties of nanocrystalline CdSe thin films prepared by thermal vacuum evaporation

Photoconductivity and photoluminescence in chemically deposited (Cd‐Zn)S:CdCl₂,Tb films

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Effects of Adsorption of Gaseous Ambients on the Photoluminescence Intensity of a Powdered CdS:Te Phosphor

Cited by 10 publications

References 1 publication

Photoconductivity and photoluminescence in chemically deposited films of CdSSe:CdCl2,Ho

Photoconductivity and photoluminescence in chemically deposited films of CdSSe:CdCl2,Ho

Electrical properties of nanocrystalline CdSe thin films prepared by thermal vacuum evaporation

Photoconductivity and photoluminescence in chemically deposited (Cd‐Zn)S:CdCl2,Tb films

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Product

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Photoconductivity and photoluminescence in chemically deposited (Cd‐Zn)S:CdCl₂,Tb films