V - Positron Annihilation in Halle

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Voids in GaAs • Molecular-dynamic cluster calculations give energy gain compared to sum of monovacancies • Relaxation was taken into account • Energetically favored: 12 vacancies • Positron lifetime was calculated • stable 12-atom cluster exhibit positron lifetime of about 450 ps • Found in experiment Martin-Luther-Universität Halle TEM Staab et al., Physica B 273-274 (1999) 501-504
Coincidence Coincidence-Doppler Doppler Spectroscopy at GaAs:Cu • In high-momentum region (>10-2 2 m m0c) c) annihilation with Coreelectrons dominate 0 • Electron momentum distribution of core electrons almost not changed compared to individual atoms 1,00 • Rlti Relatively l easy to t calculate l lt • In example: the detected vacancies have Cu atoms in closest vicinityy 075 0,75 • Vacancies are obviously stabilized by Cu Martin-Luther-Universität Halle Raatio to bulkk GaAs 4 Cu V Ga -Si Ga SI-GaAs:Cu (annealed, at 500 K) SI-GaAs:Cu (as quenched, at 30 K) 0 10 20 p (10 L 30 -3 m c) 0 V. Bondarenko, K. Petters, R. Krause Krause-Rehberg, Rehberg, J. Gebauer, H.S. Leipner, Physica B 308-310 (2001)792-795
Page 1 and 2: Defect Characterization in Crystall
Page 3 and 4: • Vacancy concentration in therma
Page 5 and 6: Defects in electron-irradiated elec
Page 7 and 8: GaAs: annealing under defined As As
Page 9 and 10: Comparison of doped and undoped GaA
Page 11 and 12: Theoretical Calculation of Vacancy
Page 13 and 14: Defects after high energy Si self s
Page 15 and 16: First defect-depth defect depth pro
Page 17: Determination of Defect Type 280

V - Positron Annihilation in Halle

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