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Journal ArticleDOI

Structural and optical properties of Mn-doped CdS thin films prepared by ion implantation

17 Jun 2009-Journal of Applied Physics (American Institute of Physics)-Vol. 105, Iss: 12, pp 123507
TL;DR: In this article, structural and optical properties of Mn-doped CdS thin films prepared by 190 keV Mn-ion implantation at different temperatures were investigated and shown to exhibit a new band in their photoluminescence spectra at 2.22 eV which originates from the d-d transition of tetrahedrally coordinated Mn2+ ions.
Abstract: We report on structural and optical properties of Mn-doped CdS thin films prepared by 190 keV Mn-ion implantation at different temperatures. Mn-ion implantation in the fluence range of 1×1013–1×1016 ions cm−2 does not lead to the formation of any secondary phase. However, it induces structural disorder, causing a decrease in the optical band gap. This is addressed on the basis of band tailing due to creation of localized energy states and Urbach energy calculations. Mn-doped samples exhibit a new band in their photoluminescence spectra at 2.22 eV, which originates from the d-d (T41→A61) transition of tetrahedrally coordinated Mn2+ ions.
Citations
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Journal ArticleDOI
TL;DR: In this article, a review highlights work over the past several years to improve the photocatalytic efficiency and stability of CdS for hydrogen (H2) production from water.
Abstract: Over the past few years, many approaches have been developed progressively to produce hydrogen (H2) from water under solar light irradiation. This process of fuel production is clean, potentially cost-effective, and environment-friendly. At present, however, current technologies are unable to meet the industrial requirements because of high cost, low photoresponse, and insufficient catalytic performance. Among water splitting photocatalysts, CdS is considered to be an interesting and important material owing to its low cost, prominent catalytic activity, high absorption in the visible spectrum, and the suitable positions of its conduction (CB) and valence (VB) bands. There are, however, some associated problems such as the rapid recombination of photogenerated electron–hole pairs and photocorrosion that have severely hampered its practical usage. The efficient conversion of water to H2 depends on the extent to which the charge carriers, especially the electrons, are first generated and then have sufficient life-time for their effective utilization. This review highlights work over the past several years to improve the photocatalytic efficiency and stability of CdS for H2 production from water.

148 citations

Journal ArticleDOI
TL;DR: In this article, the synthesis, characterization and photoluminescence (PL) studies of Mn doped ZnS nanoparticles prepared by chemical precipitation method using mercaptoethanol as a capping agent were reported.

68 citations

Journal ArticleDOI
TL;DR: In this paper, the average particle size calculated from band gap values is in good agreement with the TEM study calculation and it is around 4-5 nm, whereas for CdS:Cr nanoparticles, a broad emission band with a maximum at similar to 587 nm is observed.

66 citations

Journal ArticleDOI
TL;DR: In this article, a cubic zinc blende structure of CdS:Mn as primary phase and cubic structured α-MnS as secondary phase was revealed by X-ray diffraction.

63 citations

Journal ArticleDOI
TL;DR: In this paper, the formation of hexagonal phase CdS films with good crystallinity was confirmed by vibrational spectroscopy analysis, which showed the homogeneous presence of Cu in final film and the optical transparency of fabricated films was noticed in range of 60 to 80%.

52 citations

References
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Journal ArticleDOI
TL;DR: In this paper, the physical properties of diluted magnetic semiconductors (DMS) of the type AII1−xMnxBVI (e.g., Cd1−mnxSe, Hg 1−mnsTe) were reviewed.
Abstract: We review the physical properties of diluted magnetic semiconductors (DMS) of the type AII1−xMnxBVI (e.g., Cd1−xMnxSe, Hg1−xMnxTe). Crystallographic properties are discussed first, with emphasis on the common structural features which these materials have as a result of tetrahedral bonding. We then describe the band structure of the AII1−xMnxBVI alloys in the absence of an external magnetic field, stressing the close relationship of the sp electron bands in these materials to the band structure of the nonmagnetic AIIBVI ‘‘parent’’ semiconductors. In addition, the characteristics of the narrow (nearly localized) band arising from the half‐filled Mn 3d5 shells are described, along with their profound effect on the optical properties of DMS. We then describe our present understanding of the magnetic properties of the AII1−xMnxBVI alloys. In particular, we discuss the mechanism of the Mn++‐Mn++ exchange, which underlies the magnetism of these materials; we present an analytic formulation for the magnetic susc...

2,895 citations

Journal ArticleDOI
TL;DR: Theoretical size and strain profile functions are given by the minimum number of parameters required by physics and are compared with TEM results as mentioned in this paper, which provides crystallite size, size distribution and dislocation structure.

752 citations

Journal ArticleDOI
TL;DR: In this article, the authors summarize recent progress in dilute magnetic semiconductors (DMS) such as (Ga, Mn)N, (Ga and Mn)P, (Zn, Mn), O, and SiGeN2 exhibiting room temperature ferromagnetic properties.
Abstract: Existing semiconductor electronic and photonic devices utilize the charge on electrons and holes in order to perform their specific functionality such as signal processing or light emission. The relatively new field of semiconductor spintronics seeks, in addition, to exploit the spin of charge carriers in new generations of transistors, lasers and integrated magnetic sensors. The ability to control of spin injection, transport and detection leads to the potential for new classes of ultra-low power, high speed memory, logic and photonic devices. The utility of such devices depends on the availability of materials with practical (>300 K) magnetic ordering temperatures. In this paper, we summarize recent progress in dilute magnetic semiconductors (DMS) such as (Ga, Mn)N, (Ga, Mn)P, (Zn, Mn)O and (Zn, Mn)SiGeN2 exhibiting room temperature ferromagnetism, the origins of the magnetism and its potential applications in novel devices such as spin-polarized light emitters and spin field effect transistors.

438 citations

Journal ArticleDOI
TL;DR: In this paper, the structural and magnetic properties of Co-and Ni-implanted ZnO single crystals were investigated and it was shown that Co or Ni nanocrystals (NCs) are the major contribution of the measured ferromagnetic properties.
Abstract: In the last decade, transition-metal-doped ZnO has been intensively investigated as a route to room-temperature diluted magnetic semiconductors (DMSs). However, the origin for the reported ferromagnetism in ZnO-based DMS remains questionable. Possible options are diluted magnetic semiconductors, spinodal decomposition, or secondary phases. In order to clarify this question, we have performed a thorough characterization of the structural and magnetic properties of Co- and Ni-implanted ZnO single crystals. Our measurements reveal that Co or Ni nanocrystals (NCs) are the major contribution of the measured ferromagnetism. Already in the as-implanted samples, Co or Ni NCs have formed and they exhibit superparamagnetic properties. The Co or Ni NCs are crystallographically oriented with respect to the ZnO matrix. Their magnetic properties, e.g., the anisotropy and the superparamagnetic blocking temperature, can be tuned by annealing. We discuss the magnetic anisotropy of Ni NCs embedded in ZnO concerning the strain anisotropy.

173 citations

Journal ArticleDOI
TL;DR: In this paper, a brief overview is provided, focusing on Mn2+-doped II-VI semiconductor nanocrystals prepared by direct chemical synthesis and capped with coordinating surface ligands.

147 citations