[1] Kang S H,Hwang D K, Park S J. Low-resistance and highly transparent Ni/indium-tin oxide ohmic contacts to phosphorous-doped p-type ZnO[J]. Appl. Phys. Lett., 2005, 86(21): 211902-211902-3.

[2] Deng B,Guo Z, Sun H. Theoretical study of Fe-doped p-type ZnO[J]. Appl. Phys. Lett., 2010, 96(17): 172106-172106-3.

[3] Deng B,Sun H Q, Guo Z Y, et al. Theoretical analysis on the improvement of p-type ZnO by B-N codoping[J]. Acta Phys. Sinica, 2010, 2: 520-526.

[4] Yamamoto T,Katayama-Yoshida H. Solution using a codoping method to unipolarity for the fabrication of p-type ZnO[J]. Japanese J. Appl. Phys., 1999, 38(2B): L166.

[5] Sun H Q,Ding S F, Wang Y T, et al. Structural, energetical and electronic properties of CdO and CdxZn1-xO compounds[J]. Acta Phys.-Chim. Sinica, 2008, 24(7): 1233-1238.

[6] Chen L L,Lu J G, Ye Z Z, et al. p-type behavior in In-N codoped ZnO thin films[J]. Appl. Phys. Lett., 2005, 87(25): 252106-252106-3.

[7] Bian J M,Li X M, Gao X D, et al. Deposition and electrical properties of N-In codoped p-type ZnO films by ultrasonic spray pyrolysis[J]. Appl. Phys. Lett., 2004, 84(4): 541-543.

[8] Ye H B,Kong J F, Shen W Z, et al. Origins of shallow level and hole mobility in codoped p-type ZnO thin films[J]. Appl. Phys. Lett., 2007, 90(10): 102115-102115-3.

[9] Tsukazaki A,Saito H, Tamura K, et al. Systematic examination of carrier polarity in composition spread ZnO thin films codoped with Ga and N[J]. Appl. Phys. Lett., 2002, 81(2): 235-237.

[10] Nakahara K,Takasu H, Fons P, et al. Interactions between gallium and nitrogen dopants in ZnO films grown by radical-source molecular-beam epitaxy[J]. Appl. Phys. Lett., 2001, 79(25): 4139-4141.

[11] Sanmyo M,Tomita Y, Kobayashi K. Preparation of p-type ZnO films by doping of Be-N bonds[J]. Chem. of Mater., 2003, 15(4): 819-821.

[12] Li J B,Wei S H, Li S S, et al. Design of shallow acceptors in ZnO: First-principles band-structure calculations[J]. Phys. Rev. B, 2006, 74(8): 081201-081204.

[13] Lu J G,Zhang Y Z, Ye Z Z, et al. Low-resistivity, stable p-type ZnO thin films realized using a Li-N dual-acceptor doping method[J]. Appl. Phys. Lett., 2006, 88(22): 222114-222114-3.

[14] Kanai Y.Admittance spectroscopy of ZnO crystals containing Ag[J]. Japanese J. Appl. Phys., 1991, 30(9R): 2021-2022.

[15] Kang H S,Ahn B D, Kim J H, et al. Structural, electrical, and optical properties of p-type ZnO thin films with Ag dopant[J]. Appl. Phys. Lett.,2006, 88(20): 202108-202108-3.

[16] Wang B,Zhao Y, Min J H, et al. Ag-N dual-accept doping for the fabrication of p-type ZnO[J]. Appl. Phys. A, 2009, 94(4): 715-718.

[17] Huang L M,Rosa A L, Ahuja R. Ferromagnetism in Cu-doped ZnO from first-principles theory[J]. Phys. Rev. B, 2006, 74(7): 075206-075211.

[18] Paudel T R,Lambrecht 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): 205202-205210.

[19] Wang Q,Sun Q, Jena P, et al. First-principles study of magnetic properties in V-doped ZnO[J]. Appl. Phys. Lett., 2007, 91(6): 063116-063116-3.

[20] Born M,Huang K. Dynamical theory of crystal lattices[M]. Oxford: Clarendon Press, 1954.

[21] Hartree D R.The wave mechanics of an atom with a non-coulomb central field. part I. theory and methods[J]. Cambridge Philosophical Society, 1928, 24(01): 89-110.

[22] Fock V. Z.Physik[J] 1930, 61: 126-130.

[23] Hohenberg P,Kohn W. Inhomogeneous electron gas[J]. Phys. Rev., 1964, 136(3B): 864-871.

[24] Kohn W,Sham L J. Self-consistent equations including exchange and correlation effects[J]. Phys. Rev., 1965, 140(4A): A1133-A1138.

[25] Perdew J P,Wang Y. Accurate and simple density functional for the electronic exchange energy: Generalized gradient approximation[J]. Phys. Rev. B, 1986, 33(12): 8800-8802.

[26] Perdew J P,Burke K, Ernzerhof M. Generalized gradient approximation made simple[J]. Phys. Rev. Lett., 1996, 77(18): 3865-3868.

[27] Vanderbilt D.Soft self-consistent pseudopotentials in a generalized eigenvalue formalism[J]. Phys. Rev. B, 1990, 41(11): 7892-7895.

[28] Segall M D,Lindan P J D, Probert M J, et al. First-principles simulation: ideas, illustrations and the CASTEP code[J]. J. Phys.: Condensed Matter, 2002, 14(11): 2717-2744.

[29] Decremps F,Datchi F, Saitta A M, et al. Local structure of condensed zinc oxide[J]. Phys. Rev. B, 2003, 68(10): 104101-104110.

[30] Jaffe E,Snydern J A, Lin Z, et al. LDA and GGA calculations for high-pressure phase transitions in ZnO and MgO[J], Phys. Rev. B, 2000, 62(3): 1660-1665.

[31] Erhart P,Albe K, Klein A. First-principles study of intrinsic point defects in ZnO: Role of band structure, volume relaxation, and finite-size effects[J]. Phys. Rev. B, 2006, 73(20): 205203-205211.

[32] Wei S H,Zunger A. Role of metal d states in Ⅱ-Ⅵ semiconductors[J]. Phys. Rev. B, 1988, 37(15): 8958-8981.

[33] Schroer P,Krüger P, Pollmann J. First-principles calculation of the electronic structure of the wurtzite semiconductors ZnO and ZnS[J]. Phys. Rev. B, 1993, 47(12): 6971-6980.

[34] Vogel D,Krüger P, Pollmann J. Ab initio electronic-structure calculations for Ⅱ-Ⅵ semiconductors using self-interaction-corrected pseudopotentials[J]. Phys. Rev. B, 1995, 52(20): R14316-R14319.

[35] Cui X Y,Medvedeva J E, Delley B, et al. Role of embedded clustering in dilute magnetic semiconductors: Cr doped GaN[J]. Phys. Rev. Lett., 2005, 95(25): 256404-256407.

[36] Barnes T M,Olson K, Wolden C A. On the formation and stability of p-type conductivity in nitrogen-doped zinc oxide[J]. Appl. Phys. Lett., 2005, 86(11): 112112-112114.

[37] Zuo C Y,Wen J, Bai Y L. First-principles investigation of N-Ag co-doping effect on electronic properties in p-type ZnO[J]. Chinese Phys. B, 2010, 19(4): 047101-047104.