ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation, and gamma-induced positron spectroscopy

The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided bulk luminescence measurements that were not affected by surface states. The origin of a green emission, the dominant trap emission in ZnO, was then investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials. The measurements showed a single positron decay curve with a 175 ps lifetime component that was attributed to Zn vacancies passivated by hydrogen. Both oxygen vacancies and hydrogen-decorated Zn vacancies were suggested to contribute to the green emission. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE. This study reports the first application of GIPS to semiconductors, and it reveals the great benefits of the XRIL technique for the study of emission and scintillation properties of materials.

[1]  K. Lynn,et al.  Nature of native defects in ZnO. , 2007, Physical review letters.

[2]  S. Jokela,et al.  Defects in ZnO , 2009 .

[3]  F. Selim,et al.  Positron lifetime measurements by proton capture , 2005 .

[4]  Kelvin G. Lynn,et al.  Superfast timing performance from ZnO scintillators , 2003 .

[5]  L. Schmidt‐Mende,et al.  ZnO - nanostructures, defects, and devices , 2007 .

[6]  F. Selim,et al.  Donor characterization in ZnO by thermally stimulated luminescence , 2014 .

[7]  F. Selim,et al.  Development of accelerator-based γ-ray-induced positron annihilation spectroscopy technique , 2005 .

[8]  Priya Maheshwari,et al.  Photon induced positron annihilation spectroscopy: A nondestructive method for assay of defects in large engineering materials , 2012 .

[9]  O. Melikhova,et al.  Defects Studies of ZnO Single Crystals Prepared by Various Techniques , 2014 .

[10]  I. V. Khodyuk,et al.  Optical, luminescence, and scintillation properties of ZnO and ZnO:Ga ceramics , 2008, 1009.1324.

[11]  J. Musarrat,et al.  Non-hydrolytic synthesis and photo-catalytic studies of ZnO nanoparticles , 2011 .

[12]  J. Valenta,et al.  Origin of green luminescence in hydrothermally grown ZnO single crystals , 2015 .

[13]  Shikuan Yang,et al.  Blue Luminescence of ZnO Nanoparticles Based on Non‐Equilibrium Processes: Defect Origins and Emission Controls , 2010 .

[14]  S. Kurosawa,et al.  Optical and scintillation properties of bulk ZnO crystal , 2012 .

[15]  F. Ren,et al.  Characteristics of unannealed ZnMgO /ZnO p-n junctions on bulk (100) ZnO substrates , 2005 .

[16]  John Wilkinson,et al.  The oscillator strength of extended exciton states and possibility for very fast scintillators , 2005 .

[17]  D. Look,et al.  Evidence of the Zn vacancy acting as the dominant acceptor in n-type ZnO. , 2003, Physical review letters.

[18]  E. Choi,et al.  Self-Styled ZnO Nanostructures Promotes the Cancer Cell Damage and Supresses the Epithelial Phenotype of Glioblastoma , 2016, Scientific Reports.

[19]  H. C. Ong,et al.  Photoluminescence and cathodoluminescence studies of stoichiometric and oxygen-deficient ZnO films , 2001 .

[20]  Young-soon Kim,et al.  Photocatalytic activity of zinc oxide micro-flowers synthesized via solution method , 2011 .

[21]  Sanjay Singh,et al.  Enhanced power factor and reduced thermal conductivity of a half-Heusler derivative Ti9Ni7Sn8: A bulk nanocomposite thermoelectric material , 2015 .

[22]  F. Selim,et al.  Cu-doping of ZnO by nuclear transmutation , 2011 .

[23]  Y. Alivov,et al.  Green luminescence band of zinc oxide films copper-doped by thermal diffusion , 2004 .

[24]  Chen,et al.  Effect of thermochemical reduction on the electrical, optical-absorption, and positron-annihilation characteristics of ZnO crystals. , 1992, Physical review. B, Condensed matter.

[25]  S. Derenzo,et al.  Development of ZnO:Ga as an ultra-fast scintillator , 2009 .

[26]  F. Fiedler,et al.  Positron-Annihilation Lifetime Spectroscopy using Electron Bremsstrahlung , 2015 .

[27]  W. Skorupa,et al.  Positron lifetimes in ZnO single crystals , 2007 .

[28]  S. Derenzo,et al.  Comparative investigation of the performance of ZnO-based scintillators for use as α-particle detectors , 2006 .

[29]  F. Selim,et al.  X-ray luminescence based spectrometer for investigation of scintillation properties. , 2012, The Review of scientific instruments.

[30]  Anderson Janotti,et al.  Fundamentals of zinc oxide as a semiconductor , 2009 .

[31]  Nicholas A. Lockerbie,et al.  Nuclear Instruments and Methods in Physics Research A , 2014 .

[32]  L. Weston,et al.  Characteristics of point defects in the green luminescence from Zn- and O-rich ZnO , 2012 .

[33]  Gamma-induced Positron Spectroscopy (GiPS) at a superconducting electron linear accelerator , 2011 .

[34]  H. Morkoç,et al.  A COMPREHENSIVE REVIEW OF ZNO MATERIALS AND DEVICES , 2005 .

[35]  V. Havranek,et al.  Characterisation of irradiation-induced defects in ZnO single crystals , 2016 .

[36]  J. Grenzer,et al.  Identification of Zn-vacancy-hydrogen complexes in ZnO single crystals: A challenge to positron annihilation spectroscopy , 2009 .

[37]  Z. A. Munir,et al.  Investigation of ZnO-Based Polycrystalline Ceramic Scintillators for Use as $\alpha$ -Particle Detectors , 2009, IEEE Transactions on Nuclear Science.

[38]  A. Vedda,et al.  Development of novel scintillator crystals , 2006 .

[39]  A. Hartmann,et al.  Positron annihilation spectroscopy using high‐energy photons , 2010 .

[40]  R. Krause-Rehberg,et al.  Positron Annihilation in Semiconductors , 1999 .

[41]  F. Fiedler,et al.  Annihilation Lifetime Spectroscopy Using Positrons from Bremsstrahlung Production , 2012 .

[42]  E. Choi,et al.  ZnO nanoparticles induces cell death in malignant human T98G gliomas, KB and non-malignant HEK cells. , 2013, Journal of biomedical nanotechnology.

[43]  A. Yoshikawa,et al.  Luminescence characteristics of the LPE‐grown undoped and In‐doped ZnO thin films and bulk single crystals , 2007 .