Structural peculiarities and point defects of bulk-ZnO single crystalsстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 11 августа 2015 г.
Аннотация:ZnO single crystals are related to promising direct wide band gap semiconductor materials belonging to the A(II)B(VI) type of compounds with wurtzite structure. "Unintentional" n-type conductivity in ZnO may be caused by zinc and oxygen vacancies, and interstitial zinc atoms. To date, the comprehensive structural investigation and analysis of point defects in ZnO is absent in literature. Green, light green and almost colorless ZnO single crystals grown by the hydrothermal method in concentrated alkali solutions 4M(KOH) + 1M(LiOH) + 0.1M(NH4OH) on monohedral seeds [0001] at crystallization temperatures in the range of 330-350 degrees C and pressures in the range of 30-50 MPa have been firstly investigated by neutron diffraction. It was revealed the presence of additional reflections (similar to 12-similar to 16%) for all the crystals caused by kinetic growth effects that give grounds to assign them to the space group P3 rather than to P6(3)mc. Analysis of the refined compositions together with the color of ZnO crystals does not rule out the relationship between the color and vacancies in the zinc and oxygen positions whose concentration decreases with the discoloration of the samples. The analysis of the photoinduced variation of the total and on-axis transmittance versus the CW laser intensity showed that the colored samples have profound deep defects related to oxygen vacancies. (C) 2014 Elsevier B.V. All rights reserved.