Structural, optical and photoluminescence properties of ZnS: Cu nanoparticle thin films as a function of dopant concentration and quantum confinement effect

National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi-110 012, India
Crystal Research and Technology (Impact Factor: 1.16). 10/2007; 42(10):976 - 982. DOI: 10.1002/crat.200710950

ABSTRACT Thin films of ZnS: Cu nanoparticles were deposited in chemical bath by a pH controlled solution synthesis technique. The copper concentration was varied from 0 to 0.1M%. XRD and SEM indicated variations in diffracted intensity and morphology with Cu concentration. The PL spectrum of the undoped ZnS nanoparticles showed emission peaks at 393 and 432nm that could be attributed to the intrinsic defect states of ZnS nanoparticles. For ZnS: Cu samples three peaks in the range of 390nm, 480nm and 525nm were observed. With increase in Cu concentration from 0.001 to 0.1M%, the peak position of 480nm and 525nm did not change, whereas 390nm peak red shifted to longer wavelength region to 422nm. In addition, it was found that the overall photoluminescence intensity reached maximum at 0.01M% and quenched with further increase in Cu concentration. Enhancement of blue and green light emission by seven and twenty fivefold respectively compared to undoped ZnS was observed in ZnS: Cu with optimal dopant concentration. Time resolved decay of photoluminescence showed faster decay for 390 – 420nm purple/ blue emission compared to green (525nm) Cu related emission which is in the microsecond time scale. Optical absorption measurements indicate enhancement of band gap (3.89eV) for undoped ZnS suggesting the quantum confinement effect in the developed nanoparticles of size below the Bohr diameter. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper gives detailed view on the Nanoelectronics and the approaches adopted for improving the speed of the device without compromising the performance. Performance of the device is mainly based on the speed of operation, Operating voltage and size of the device. In the recent years the two main approaches adopted for optimizing the device performance are new and modified device architectures and using alternate materials which are different from the normal materials used for electronics. Device structures have been modified and designed according to the application. Device modelling is the approach adopted by various companies and research groups in the universities to modify and design new device structures using device modelling and simulation software's. Performance of the device can be improved by using alternate materials such as GaAs, ZnO, BiTe, In, TiO, Fe, Co, Al, Zr etc. Materials other than silicon and germanium with better optoelectronic and electronic properties have been used to improve the performance of the device. The property of the materials can be improved by doping different materials at different compositions and preparing nanomaterials by using different preparation techniques. Materials property is analyzed by using different characterization techniques such as XRD, SEM, TEM, UV, LCR, etc.
    International Conference on Sustainable Energy and Intelligent Systems (SEISCON 2011); 01/2011
  • Source
  • [Show abstract] [Hide abstract]
    ABSTRACT: The classical thermally driven transition from supermagnetic to blocked supermagnetic and quantum phase transition from magnetic long-range order to quantum superparamagnetic state have been observed in ultrasmall In2S3:Ce diluted magnetic semiconductors (DMSs). The In2S3:Ce nanoparticles (5-6 nm) were synthesized by a facile gas-liquid phase chemical deposition process using Ce(COOCH3)3, In(COOCH3)3 and H2S as source materials. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM) were used to characterize the structure, components, morphology and size. Photoluminescence emission spectroscopy (PL) demonstrates that the luminescence quantum efficiency increases with Ce addition and indicates the existence of Ce atoms in the structure. The magnetic properties reflect a strong f-f exchange interaction between the Ce ions. The Ce doped In2S3 nanoparticles are shown to exhibit a higher blocking temperature from superparamagnetic to magnetic long-range order state, and even show room-temperature ferromagnetism. The larger ionic radius of Ce results in a larger influence on carrier concentration, affecting the blocking temperature of the magnetic phase transition.
    CrystEngComm 01/2014; 16(13):2584. DOI:10.1039/c3ce42369g · 3.86 Impact Factor

Full-text (2 Sources)

Available from
Jun 5, 2014