ZnO中氧空位缺陷形成能的第一性原理研究
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摘要
采用基于密度泛函理论的第一性原理方法,研究了ZnO在富氧和富锌条件下氧的单空位、双空位和三空位缺陷的形成能.结果表明:在富氧和富锌条件下,随着氧空位浓度的增加,氧空位形成能变大,说明ZnO中不容易产生多空位氧缺陷;随着氧空位浓度的增加,氧空位对应的吸收光谱红移;分散型氧双空位的形成能低于聚集型氧双空位,说明ZnO中不容易产生氧空位聚集,由此可解释ZnO的抗辐照能力;在富锌条件下,聚集型氧双空位的形成能大于分散型氧三空位的形成能,说明在此条件下聚集型氧双空位更难形成.
The studies on the distribution of single-and multi-vacancies of oxygen in ZnO are helpful in understanding the mechanism of the n-type conductivity of native ZnO material as well as the abilities of the radiation resistance of ZnO.In this paper,we employed the first-principles method based on the density functional theory to determine the formation energies of monovacancy,divacancies and trivacancies of oxygen in bulk ZnO under both O-rich and Zn-rich conditions.The results show that,under both O-rich and Zn-rich conditions,the formation energies of oxygen vacancy increase as the concentration of oxygen vacancy increase,indicating that it is difficult to form multi-vacancies of oxygen in bulk ZnO.With the increase of the concentration of oxygen vacancies,the absorption spectra of oxygen vacancies show red shift.For the oxygen divacancies in ZnO,the formation energy of separated oxygen vacancies is lower than that of gathered oxygen vacancies,indicating that it is not easy to produce oxygen vacancy aggregation in ZnO,which is able to explain the radiation hardness properties of ZnO.Under the Zn-rich condition,the formation energy of gathered divacancies of oxygen is greater than that of separated trivacancies,showing that oxygen vacancies are more difficult to gather under the Zn-rich condition.
The studies on the distribution of single-and multi-vacancies of oxygen in ZnO are helpful in understanding the mechanism of the n-type conductivity of native ZnO material as well as the abilities of the radiation resistance of ZnO.In this paper,we employed the first-principles method based on the density functional theory to determine the formation energies of monovacancy,divacancies and trivacancies of oxygen in bulk ZnO under both O-rich and Zn-rich conditions.The results show that,under both O-rich and Zn-rich conditions,the formation energies of oxygen vacancy increase as the concentration of oxygen vacancy increase,indicating that it is difficult to form multi-vacancies of oxygen in bulk ZnO.With the increase of the concentration of oxygen vacancies,the absorption spectra of oxygen vacancies show red shift.For the oxygen divacancies in ZnO,the formation energy of separated oxygen vacancies is lower than that of gathered oxygen vacancies,indicating that it is not easy to produce oxygen vacancy aggregation in ZnO,which is able to explain the radiation hardness properties of ZnO.Under the Zn-rich condition,the formation energy of gathered divacancies of oxygen is greater than that of separated trivacancies,showing that oxygen vacancies are more difficult to gather under the Zn-rich condition.
引文
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[2]SUCHEA M,CHRISTOULAKIS S,MOSCHOVIS K,et al.ZnO transparent thin films for gas sensor applications[J].Thin Solid Films,2006,515(2):551-554.
[3]SONG D,ABERLE A G,XIA J.Optimisation of ZnO:Al films by change of sputter gas pressure for solar cell application[J].Appl Surf Sci,2002,195(1/2/3/4):291-296.
[4]WANG Z L,SONG J H.Piezoelectric nanogenerators based on zinc oxide nanowire arrays[J].Science,2006,312(5771):242-246.
[5]OZGUR U,ALIVOV Y I,LIU C,et al.A comprehensive review of ZnO materials and devices[J].J Appl Phys,2005,98(4):041301.
[6]MAEDA K,SATO M,NIIKURA I.Growth of 2inch ZnO bulk single crystal by the hydrothermal method[J].Semicond Sci Technol,2005,20(4):S49-S54.
[7]WANG Z L.Nanostructures of zinc oxide[J].Mater Today,2004,7(6):26-33.
[8]JANOTTI A,VAN DE WALLE C G.Native point defects in ZnO[J].Phys Rev B,2007,76(16):165202.
[9]LIU L S,MEI Z X,TANG A H,et al.Oxygen vacancies:the origin of n-type conductivity in ZnO[J].Phys Rev B,2016,93(23):235305.
[10]OBA F,TOGO A,TANAKA I,et al.Defect energetics in ZnO:a hybrid Hartree-Fock density functional study[J].Phys Rev B,2008,77(24):245202.
[11]PAUDEL T R,LAMVRECHT W R L.First-principles calculation of the O vacancy in ZnO:a self-consistent gap-corrected approach[J].Phys Rev B,2008,77(20):205202.
[12]LANY S,ZUNGER A.Many-body GW calculation of the oxygen vacancy in ZnO[J].Phys Rev B,2010,81(11):113201.
[13]JANOTTI A,VAN DE WALLE C G.Oxygen vacancies in ZnO[J].Applied Physics Letters,2005,87(12):122102.
[14]CLARK S J,ROBERTSON J,LANY S.Intrinsic defects in ZnO calculated by screened exchange and hybrid density functionals[J].Phys Rev B,2010,81(11):115311.
[15]侯清玉,郭少强,赵春旺.氧空位浓度对ZnO电子结构和吸收光谱影响的研究[J].物理学报,2014,63(14):147101.
[16]LOOK D C,REYNOLDS D C,HEMSKY J W.Production and annealing of electron irradiation damage in ZnO[J].Applied Physics Letters,1999,75(6):811-813.
[17]KRESSE G,JOBERT D.From ultrasoft pseudopotentials to the projector augmented-wave method[J].Phys Rev B,1999,59(3):1758-1775.
[18]PERDEW J P,BURKE K,ERNZERHOF M.Generalized gradient approximation made simple[J].Phys Rev Lett,1996,77(18):3865-3868.
[19]PERDEW J P,CHEVARY J A,VOSKO S H,et al.Atoms,molecules,solids,and surfaces applications of the generalized gradient approximation for exchange and correlation[J].Phys Rev B,1992,46(11):6671-6687.
[20]MONKHORST H J,PARK J D.Special points for Brillouin-zone integrations[J].Phys Rev B,1976,13(12):5188-5192.
[21]VAN DE WALLE C G,NEUGEBAUER J.First-principles calculations for defects and impurities:applications toⅢ-nitrides[J].Journal of Applied Physics,2004,95(8):3851-3879.
[22]KOHAN A F,CEDER G,MORGAN D,et al.Firstprinciples study of native point defects in ZnO[J].Phys Rev B,2000,61(22):15019-15027.
[23]ZHAO J L,ZHANG W Q,LI X M,et al.Convergence of the formation energies of intrinsic point defects in wurtzite ZnO:first-principles study by projector augmented wave method[J].Journal of Physics:Condensed Matter,2006,18(5):1495-1508.
[24]MADELUNG O,SCHULZ M,WEISS H.Numerical data and functional relationships in science and technology[M].Berlin:Springer-Verlag,1982:17.
[25]HALLIBURTON L E,GILES N C,GARCES N Y,et al.Production of native donors in ZnO by annealing at high temperature in Zn vapor[J].Applied Physics Letters,2005,87(17):172108.