Cobalt (Co) doped AZO (2 at.% Al doped ZnO) thin films were synthesized by sol-gel technique. The films were found to have polycrystalline wurtzite structure of ZnO. The structural, morphological and transport properties of the films were investigated and found to be strongly composition dependent. Grain size and room temperature resistivity of the films were found to decrease with increase of Co content in the AZO films from 1 to 3 at.%. Beyond 3 at.% these parameters were found increasing. The electrical resistivity of the films was measured down to temperature of 100 K. The carrier transport mechanisms have been explained on the basis of thermionic emission and variable range hopping. © 2009 Elsevier B.V. All rights reserved.

SUDIPTA BANDYOPADHYAY

Physics

S K NEOGI

R GHOSH

G K PAUL

S K BERA

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Journal of Alloys and Compounds

3 at.% Co doped sol-gel derived films were irradiated with 800 keV Ar ion beam. The studied films were un-irradiated and irradiated with fluences 5 × 10 ¹⁴ , 2.5 × 10 ¹⁵ and 10 ¹⁶ ions/cm ² . The films were characterized structurally (X-ray diffraction [XRD]), morphologically (Field Induced Scanning Electron Microscopy), optically (UV–visible, Raman spectroscopy and Photoluminescence [PL] measurements), magnetically (field and temperature dependent magnetization measurements) and electronically via local structure study (X-ray Absorption spectroscopy [XAS]). XAS data were interpreted in X-ray absorption near edge spectroscopy (XANEX) and extended X-ray absorption fine structure spectroscopy (EXAFS) measurements. XRD patterns show single-phase wurtzite structure of the films and indicate presence of defects. Raman spectra confirm single-phase structure of the films and indicate slight structural degradation in highest fluence irradiated film. The high substitutional incorporation of Co ²⁺ at Zn ²⁺ site was demonstrated from UV–visible spectra by d-d transition. The analysis of XANES and EXAFS spectra strongly reconfirms further the proper substitutional incorporation of Co ²⁺ at Zn ²⁺ site. All films are intrinsically ferromagnetic. The substantial enhancement of ferromagnetism (2.5 fold) has been observed upon irradiation (highest fluence) and it has been interpreted in terms of defects as evidenced from PL measurement. Hence the effect of Ar ion beam irradiation is highly enhanced ferromagnetism and proper Co substituted ZnO film.

Applied Surface Science

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Grain boundary defects-mediated room temperature ferromagnetism in Co-doped ZnO film

Improvement of optical properties of nanocrystalline Fe-doped ZnO powders through precipitation method from citrate-modified zinc nitrate solution

Absence of room-temperature ferromagnetism in Al-codoped Zn0.95Co0.05O nanoparticles

Effect of thickness on structural, electrical, optical and magnetic properties of Co and Al doped ZnO films deposited by sol–gel route

New Journal of Physics

Magnetic properties of sol-gel-derived doped ZnO as a potential ferromagnetic semiconductor: a synchrotron-based study

Effects of Co doping on structural, morphological and transport properties of sol-gel AZO thin films

Journal	Data powered by TypesetJournal of Alloys and Compounds
Publisher	Data powered by TypesetELSEVIER SCIENCE SA
ISSN	0925-8388
Open Access	No