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Donor-Acceptor Complexes in ZnO

Donor-Acceptor Complexes in ZnO. M. Türker , M. Deicher , H. Wolf, and Th . Wichert. Universität des Saarlandes Technische Physik, 66123 Saarbrücken. The ISOLDE Collaboration CERN, Geneva , Switzerland. Zinc Oxide. E G = 3.37 eV at RT E exciton binding = 60 meV

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Donor-Acceptor Complexes in ZnO

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  1. Donor-Acceptor Complexes in ZnO M. Türker, M. Deicher, H. Wolf, andTh. Wichert Universität des Saarlandes Technische Physik, 66123 Saarbrücken The ISOLDE Collaboration CERN, Geneva, Switzerland

  2. Zinc Oxide EG = 3.37 eV at RT Eexcitonbinding = 60 meV Bulk crystal Easy to dope n-type Difficultto dope p-type Zn NO O Bulk crystal c-axis 2

  3. Howtoenhance p-type doping? possible In-N2 complex Donor-AcceptorCodoping Yamamoto andKatayama-Yoshida Physica B 302 (2001) 155 Donor-Acceptor Cluster-Doping Wang andZunger Physical Review Letters 90 (2003) 256401 Zn NO O InZn 3

  4. Howtoenhance p-type doping? increaseby factor1000 possible In-N2 complex Donor-AcceptorCodoping Yamamoto andKatayama-Yoshida Physica B 302 (2001) 155 Donor-Acceptor Cluster-Doping Wang andZunger Physical Review Letters 90 (2003) 256401 Zn NO O ElectricalpropertiesofZnOfilms InZn Chen, Lu, Ye, Lin, Zhao, Ye, Li, andZhu Applied Physics Letters 87 (2005) 252106 3

  5. Codopingwith In and N byimplantation possible In-N2 complex SIMS depthprofiling as implanted TA=1073K t=60min 1020 1019 1018 1017 1016 Zn Concentration[ions/cm3] NO O N In In InZn In In N 0.0 0.4 0.8 1.2 0.0 0.4 0.8 1.2 depth[μm] Park, Sakaguchi, Ohashi, Hishita, andHaneda Applied Surface Science 203-204 (2003) 359 4

  6. Perturbed Angular Correlation (PAC) • Electrical • fieldgradientVij • strengthVzz • symmetryη= • orientation • EFG ~ r – 3 • - microscopiclocal Zn Zn Vxx- Vyy Vzz O O NO 111InZn 111InZn EFGlattice EFGdefect 5

  7. Perturbed Angular Correlation (PAC) 111In Donor-acceptor interaction T1/2 = 3 d EC 1 Observation T1/2 = 85 ns Q 2 111Cd 6

  8. ω2 ω3 ω1 EFG ≠ 0 e Q Vzz 10 Q= w1= 3p h Q: quadrupolecouplingconstant Perturbed Angular Correlation (PAC) 111In Donor-acceptor interaction T1/2 = 3 d EC 1 Observation T1/2 = 85 ns Q 2 111Cd 6

  9. detector detector IntrinsicEFGlatticeofZnO 111In implantation; TA = 1100K tA= 30min R(t) Fourier transforms c-axis: EFGlattice Q= 31MHz  = 0 f = 86% t [ns] w [Mrad/s] 45°-geometry 7

  10. CodopingofZnO Indium penetrationin ZnO 111In implantation; TA = 1100K tA= 30min R(t) Fourier transforms depth974 Å EFGlattice Q= 31MHz  = 0 f = 86% E = 400 keV (atoms/cm3) / (atoms/cm2) In t [ns] w [Mrad/s] depth3368 Å Group V energypenetrationdepth N 220keV 3368Å P 400keV 3179Å As Sb 400keV 1228Å E = 220 keV (atoms/cm3) / (atoms/cm2) N 8

  11. Indium-Nitrogen codopingofZnO N (220keV) + 111In (400keV); TA = 1000K tA= 20min Q2 Q1 FT(ω) R(t) Q2 Q1 FT(ω) R(t) t [ns] w [Mrad/s] 9

  12. Indium-Nitrogen codopingofZnO N (220keV) + 111In (400keV); TA = 1000K tA= 20min Q2 2 axial symmetrical EFGdefect: Q1 FT(ω) R(t) c-axisoriented Q1=209(1)MHz =0 f=2% Q2 Q1 basal plane oriented Q2=234(1)MHz ≤0 f=5% FT(ω) R(t) t [ns] w [Mrad/s] w [Mrad/s] 9

  13. f0 f2 f1 Indium-Nitrogen codopingofZnO Isochronicannealing 10

  14. Indium-PhosphoruscodopingofZnO P (400keV) + 111In (400keV); TA = 800K tA= 60min 2 axial symmetrical EFGdefect: Q2 Q1 FT(ω) R(t) c-axisoriented Q1=153(1)MHz =0 f=2% Q2 Q1 basal plane oriented Q2=176(1)MHz ≤0 f=10% FT(ω) R(t) t [ns] w [Mrad/s] 11

  15. Formation of Indium-Acceptor-Pairs in II-VI semiconductors cubic wurtzite theoretical * Ostheimer, Jost, Filz, Lauer, Wolf, and Wichert Applied Physics Letters 69 (1996) 2840 * * Lany, Ostheimer, Wolf, and Wichert Hyperfine Interactions 136/137 (2001) 619 12

  16. Formation of Indium-Acceptor-Pairs in Zinc Oxide 13

  17. In-N1 In-N2 In-N3 In-N4 Possibleconfigurationsof In-NXComplexes =0 ≤0.1 ≠0 ≠0 ≠0 =0 =0 14

  18. PAC • In-N1: 2 EFG • In-P1: 2 EFG Summary Donor–acceptorcodopingofZnObyionimplantation Aim: analysisofthemicroscopicenvironment on atomiclevel Tool: Perturbed Angular Correlationtoobtainstructuralinformation 15

  19. 77Br Group VII Donor Li Na K Group I Acceptor ISOLDE CERN Work in progress 77Br/ 77Se (60keV); TA = 1100K Q=403 MHz Implantations: Michael Uhrmacher and Daniel Jürgens (U Göttingen) Financial supportbyBMBF 05KK7TS1 16

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