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Andreas Wagner - One of the best experts on this subject based on the ideXlab platform.
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Vacancy cluster in ZnO films grown by pulsed laser deposition
Nature Publishing Group, 2019Co-Authors: Zilan Wang, Caiqin Luo, Wolfgang Anwand, Andreas Wagner, M. Butterling, Azizar M. Rahman, Matthew R. Phillips, Cuong Ton-that, M. YounasAbstract:Abstract Undoped and Ga-doped ZnO films were grown on c-sapphire using pulsed laser deposition (PLD) at the substrate temperature of 600 °C. Positron annihilation spectroscopy study (PAS) shows that the dominant VZn-Related Defect in the as-grown undoped ZnO grown with relative low oxygen pressure P(O2) is a vacancy cluster (most likely a VZn-nVO complex with n = 2, 3) rather than the isolated VZn which has a lower formation energy. Annealing these samples at 900 °C induces out-diffusion of Zn from the ZnO film into the sapphire creating the VZn at the film/sapphire interface, which favors the formation of vacancy cluster containing relatively more VZn. Increasing the P(O2) during growth also lead to the formation of the vacancy cluster with relatively more VZn. For Ga-doped ZnO films, the oxygen pressure during growth has significant influence on the electron concentration and the microstructure of the VZn-Related Defect. Green luminescence (GL) and yellow luminescence (YL) were identified in the cathodoluminescence study (CL) study, and both emission bands were quenched after hydrogen plasma treatment. The origin of the GL is discussed
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Zn-vacancy Related Defects in ZnO grown by pulsed laser deposition
Oxide-based Materials and Devices VIII, 2017Co-Authors: Francis Chi-chung Ling, Caiqin Luo, Zilan Wang, Wolfgang Anwand, Andreas WagnerAbstract:Undoped and Ga-doped ZnO (002) films were grown c-sapphire using the pulsed laser deposition (PLD) method. Znvacancy Related Defects in the films were studied by different positron annihilation spectroscopy (PAS). These included Doppler broadening spectroscopy (DBS) employing a continuous monenergetic positron beam, and positron lifetime spectroscopy using a pulsed monoenergetic positron beam attached to an electron linear accelerator. Two kinds of Znvacancy Related Defects namely a monovacancy and a divacancy were identified in the films. In as-grown undoped samples grown with relatively low oxygen pressure P(O 2 )≤1.3 Pa, monovacancy is the dominant Zn-vacancy Related Defect. Annealing these samples at 900 o C induced Zn out-diffusion into the substrate and converted the monovacancy to divacancy. For the undoped samples grown with high P(O 2 )=5 Pa irrespective of the annealing temperature and the as-grown degenerate Ga-doped sample (n=10 20 cm -3 ), divacancy is the dominant Zn-vacancy Related Defect. The clustering of vacancy will be discussed.
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Zn-Vacancy Related Defects Identified in ZnO Films Grown by Pulsed Laser Deposition
Defect and Diffusion Forum, 2017Co-Authors: Francis Chi-chung Ling, Caiqin Luo, Zilan Wang, Wolfgang Anwand, Andreas WagnerAbstract:Undoped and Cu-doped ZnO grown on sapphire using pulsed laser deposition (PLD) were studied by positron annihilation spectroscopy (PAS), photoluminescence (PL), high-resolution transmission electron microscopy (HRTEM) and secondary ion mass spectroscopy (SIMS). In the undoped samples, two kinds of VZn-Related Defects, namely VZn1 and VZn2 are identified. VZn1 was identified in as-grown samples grown at relatively low substrate (~300 °C). After annealing at 900 °C, VZn-2, the green luminescence (GL) peaking at 2.47 eV and the near band edge (NBE) emission at 3.23 eV in the low temperature photoluminescence (LT-PL) were simultaneously introduced. Another kind of VZn-Related Defect is identified in the Cu-doped ZnO sample, and is tentatively assigned to the VZn decorated with the Cu.
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the zn vacancy Related green luminescence and donor acceptor pair emission in zno grown by pulsed laser deposition
RSC Advances, 2015Co-Authors: Zilan Wang, Francis Chi-chung Ling, Wolfgang Anwand, M. Younas, Shichen Su, Andreas WagnerAbstract:A low temperature (10 K) photoluminescence study shows that green luminescence (GL) peaking at 2.47 eV and near band edge (NBE) emission at 3.23 eV are introduced in undoped ZnO grown by pulsed laser deposition (PLD) after 900 °C annealing. The NBE emission exhibiting blue shift with increasing temperature is assigned to the transitions of the donor–acceptor-pair (DAP)/free-electron-to-acceptor (FA). Positron annihilation spectroscopy (PAS) study shows that the introduction of the GL is corRelated with the formation of the Zn vacancy-Related Defect (VZn). Comparing the transition energies of VZn obtained by the previous first principles calculation [Janotti and Van de Walle, Phys. Rev. B: Condens. Matter Mater. Phys., 2007, 76, 165202], the GL is associated with the transition from the conduction band to the e(−/2−) state of VZn and the DAP/FA emission involves the acceptor level e(0/−) of VZn.
Zilan Wang - One of the best experts on this subject based on the ideXlab platform.
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Vacancy cluster in ZnO films grown by pulsed laser deposition
Nature Publishing Group, 2019Co-Authors: Zilan Wang, Caiqin Luo, Wolfgang Anwand, Andreas Wagner, M. Butterling, Azizar M. Rahman, Matthew R. Phillips, Cuong Ton-that, M. YounasAbstract:Abstract Undoped and Ga-doped ZnO films were grown on c-sapphire using pulsed laser deposition (PLD) at the substrate temperature of 600 °C. Positron annihilation spectroscopy study (PAS) shows that the dominant VZn-Related Defect in the as-grown undoped ZnO grown with relative low oxygen pressure P(O2) is a vacancy cluster (most likely a VZn-nVO complex with n = 2, 3) rather than the isolated VZn which has a lower formation energy. Annealing these samples at 900 °C induces out-diffusion of Zn from the ZnO film into the sapphire creating the VZn at the film/sapphire interface, which favors the formation of vacancy cluster containing relatively more VZn. Increasing the P(O2) during growth also lead to the formation of the vacancy cluster with relatively more VZn. For Ga-doped ZnO films, the oxygen pressure during growth has significant influence on the electron concentration and the microstructure of the VZn-Related Defect. Green luminescence (GL) and yellow luminescence (YL) were identified in the cathodoluminescence study (CL) study, and both emission bands were quenched after hydrogen plasma treatment. The origin of the GL is discussed
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Zn-vacancy Related Defects in ZnO grown by pulsed laser deposition
Oxide-based Materials and Devices VIII, 2017Co-Authors: Francis Chi-chung Ling, Caiqin Luo, Zilan Wang, Wolfgang Anwand, Andreas WagnerAbstract:Undoped and Ga-doped ZnO (002) films were grown c-sapphire using the pulsed laser deposition (PLD) method. Znvacancy Related Defects in the films were studied by different positron annihilation spectroscopy (PAS). These included Doppler broadening spectroscopy (DBS) employing a continuous monenergetic positron beam, and positron lifetime spectroscopy using a pulsed monoenergetic positron beam attached to an electron linear accelerator. Two kinds of Znvacancy Related Defects namely a monovacancy and a divacancy were identified in the films. In as-grown undoped samples grown with relatively low oxygen pressure P(O 2 )≤1.3 Pa, monovacancy is the dominant Zn-vacancy Related Defect. Annealing these samples at 900 o C induced Zn out-diffusion into the substrate and converted the monovacancy to divacancy. For the undoped samples grown with high P(O 2 )=5 Pa irrespective of the annealing temperature and the as-grown degenerate Ga-doped sample (n=10 20 cm -3 ), divacancy is the dominant Zn-vacancy Related Defect. The clustering of vacancy will be discussed.
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Zn-Vacancy Related Defects Identified in ZnO Films Grown by Pulsed Laser Deposition
Defect and Diffusion Forum, 2017Co-Authors: Francis Chi-chung Ling, Caiqin Luo, Zilan Wang, Wolfgang Anwand, Andreas WagnerAbstract:Undoped and Cu-doped ZnO grown on sapphire using pulsed laser deposition (PLD) were studied by positron annihilation spectroscopy (PAS), photoluminescence (PL), high-resolution transmission electron microscopy (HRTEM) and secondary ion mass spectroscopy (SIMS). In the undoped samples, two kinds of VZn-Related Defects, namely VZn1 and VZn2 are identified. VZn1 was identified in as-grown samples grown at relatively low substrate (~300 °C). After annealing at 900 °C, VZn-2, the green luminescence (GL) peaking at 2.47 eV and the near band edge (NBE) emission at 3.23 eV in the low temperature photoluminescence (LT-PL) were simultaneously introduced. Another kind of VZn-Related Defect is identified in the Cu-doped ZnO sample, and is tentatively assigned to the VZn decorated with the Cu.
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the zn vacancy Related green luminescence and donor acceptor pair emission in zno grown by pulsed laser deposition
RSC Advances, 2015Co-Authors: Zilan Wang, Francis Chi-chung Ling, Wolfgang Anwand, M. Younas, Shichen Su, Andreas WagnerAbstract:A low temperature (10 K) photoluminescence study shows that green luminescence (GL) peaking at 2.47 eV and near band edge (NBE) emission at 3.23 eV are introduced in undoped ZnO grown by pulsed laser deposition (PLD) after 900 °C annealing. The NBE emission exhibiting blue shift with increasing temperature is assigned to the transitions of the donor–acceptor-pair (DAP)/free-electron-to-acceptor (FA). Positron annihilation spectroscopy (PAS) study shows that the introduction of the GL is corRelated with the formation of the Zn vacancy-Related Defect (VZn). Comparing the transition energies of VZn obtained by the previous first principles calculation [Janotti and Van de Walle, Phys. Rev. B: Condens. Matter Mater. Phys., 2007, 76, 165202], the GL is associated with the transition from the conduction band to the e(−/2−) state of VZn and the DAP/FA emission involves the acceptor level e(0/−) of VZn.
Erik Janzén - One of the best experts on this subject based on the ideXlab platform.
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carbon vacancy Related Defect in 4h and 6h sic
Physical Review B, 2001Co-Authors: Tien Son Nguyen, Erik JanzénAbstract:An electron paramagnetic resonance (EPR) spectrum was observed at temperatures above 25 K in p-type 4H and 6H SiC irradiated with electrons. The center has C-3V symmetry with an electron spin S= 1/2. Using high frequency (similar to 95 GHz) EPR it was possible to obtain the derailed hyperfine structure due to the interaction with the four nearest silicon neighbors, and to identify the Defect as the carbon vacancy in the positive-charge state (VC+). The g values and hyper fine tensor of the center in both polytypes are almost the same and no dependence on the inequivalent lattice sites has been detected.
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silicon vacancy Related Defect in 4h and 6h sic
Physical Review B, 2000Co-Authors: E Sorman, Weimin Chen, Olof Kordina, Christer Hallin, Erik JanzénAbstract:We report on an irradiation-induced photoluminescence (PL) band in 4H and 6H SiC and the corresponding optically detected magnetic resonance (ODMR) signals from this band. The deep PL band has the same number of no-phonon lines as there are inequivalent sites in the respective polytype. These lines are at 1352 and 1438 meV in the case of 4H and at 1366, 1398, and 1433 meV in the case of 6H. The intensity of the PL lines is reduced after a short anneal at 750 \ifmmode^\circ\else\textdegree\fi{}C. ODMR measurements with above-band-gap excitation show that two spin-triplet $(S=1)$ states with a weak axial character are detected via each PL line in these bands. One of these two triplet states can be selectively excited with the excitation energy of the corresponding PL line. These triplet signals can therefore be detected separately and only then can the well documented and characteristic hyperfine interaction of the silicon vacancy in SiC be resolved. Considering the correlation between the irradiation dose and the signal strength, the well established annealing temperature and the characteristic hyperfine pattern, we suggest that this PL band is Related to the isolated silicon vacancy in 4H and 6H SiC. The spin state $(S=1)$ implies a charge state of the vacancy with an even number of electrons. By combining the knowledge from complementary electron-spin resonance measurements and theoretical calculations we hold the neutral charge state for the strongest candidate.
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Metastability of a Hydrogen-Related Defect in 6H-SiC
Materials Science Forum, 2000Co-Authors: Anne Henry, T. Egilsson, Ivan Gueorguiev Ivanov, Erik JanzénAbstract:We report on the metastability behavior of a hydrogen Related Defect in 6H-SiC. This Defect gives rise to a low temperature photoluminescence spectrum and several excited states have been observed using photoluminescence excitation. A quenching of the luminescence intensity is observed when using prolonged optical excitation either with energy higher than the threshold for phonon assisted free-exciton formation or when the excitation energy is resonant with an excited state of the hydrogen Related bound exciton. Depending on the initial conditions different types of behavior can be observed.
Wolfgang Anwand - One of the best experts on this subject based on the ideXlab platform.
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Vacancy cluster in ZnO films grown by pulsed laser deposition
Nature Publishing Group, 2019Co-Authors: Zilan Wang, Caiqin Luo, Wolfgang Anwand, Andreas Wagner, M. Butterling, Azizar M. Rahman, Matthew R. Phillips, Cuong Ton-that, M. YounasAbstract:Abstract Undoped and Ga-doped ZnO films were grown on c-sapphire using pulsed laser deposition (PLD) at the substrate temperature of 600 °C. Positron annihilation spectroscopy study (PAS) shows that the dominant VZn-Related Defect in the as-grown undoped ZnO grown with relative low oxygen pressure P(O2) is a vacancy cluster (most likely a VZn-nVO complex with n = 2, 3) rather than the isolated VZn which has a lower formation energy. Annealing these samples at 900 °C induces out-diffusion of Zn from the ZnO film into the sapphire creating the VZn at the film/sapphire interface, which favors the formation of vacancy cluster containing relatively more VZn. Increasing the P(O2) during growth also lead to the formation of the vacancy cluster with relatively more VZn. For Ga-doped ZnO films, the oxygen pressure during growth has significant influence on the electron concentration and the microstructure of the VZn-Related Defect. Green luminescence (GL) and yellow luminescence (YL) were identified in the cathodoluminescence study (CL) study, and both emission bands were quenched after hydrogen plasma treatment. The origin of the GL is discussed
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Zn-vacancy Related Defects in ZnO grown by pulsed laser deposition
Oxide-based Materials and Devices VIII, 2017Co-Authors: Francis Chi-chung Ling, Caiqin Luo, Zilan Wang, Wolfgang Anwand, Andreas WagnerAbstract:Undoped and Ga-doped ZnO (002) films were grown c-sapphire using the pulsed laser deposition (PLD) method. Znvacancy Related Defects in the films were studied by different positron annihilation spectroscopy (PAS). These included Doppler broadening spectroscopy (DBS) employing a continuous monenergetic positron beam, and positron lifetime spectroscopy using a pulsed monoenergetic positron beam attached to an electron linear accelerator. Two kinds of Znvacancy Related Defects namely a monovacancy and a divacancy were identified in the films. In as-grown undoped samples grown with relatively low oxygen pressure P(O 2 )≤1.3 Pa, monovacancy is the dominant Zn-vacancy Related Defect. Annealing these samples at 900 o C induced Zn out-diffusion into the substrate and converted the monovacancy to divacancy. For the undoped samples grown with high P(O 2 )=5 Pa irrespective of the annealing temperature and the as-grown degenerate Ga-doped sample (n=10 20 cm -3 ), divacancy is the dominant Zn-vacancy Related Defect. The clustering of vacancy will be discussed.
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Zn-Vacancy Related Defects Identified in ZnO Films Grown by Pulsed Laser Deposition
Defect and Diffusion Forum, 2017Co-Authors: Francis Chi-chung Ling, Caiqin Luo, Zilan Wang, Wolfgang Anwand, Andreas WagnerAbstract:Undoped and Cu-doped ZnO grown on sapphire using pulsed laser deposition (PLD) were studied by positron annihilation spectroscopy (PAS), photoluminescence (PL), high-resolution transmission electron microscopy (HRTEM) and secondary ion mass spectroscopy (SIMS). In the undoped samples, two kinds of VZn-Related Defects, namely VZn1 and VZn2 are identified. VZn1 was identified in as-grown samples grown at relatively low substrate (~300 °C). After annealing at 900 °C, VZn-2, the green luminescence (GL) peaking at 2.47 eV and the near band edge (NBE) emission at 3.23 eV in the low temperature photoluminescence (LT-PL) were simultaneously introduced. Another kind of VZn-Related Defect is identified in the Cu-doped ZnO sample, and is tentatively assigned to the VZn decorated with the Cu.
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the zn vacancy Related green luminescence and donor acceptor pair emission in zno grown by pulsed laser deposition
RSC Advances, 2015Co-Authors: Zilan Wang, Francis Chi-chung Ling, Wolfgang Anwand, M. Younas, Shichen Su, Andreas WagnerAbstract:A low temperature (10 K) photoluminescence study shows that green luminescence (GL) peaking at 2.47 eV and near band edge (NBE) emission at 3.23 eV are introduced in undoped ZnO grown by pulsed laser deposition (PLD) after 900 °C annealing. The NBE emission exhibiting blue shift with increasing temperature is assigned to the transitions of the donor–acceptor-pair (DAP)/free-electron-to-acceptor (FA). Positron annihilation spectroscopy (PAS) study shows that the introduction of the GL is corRelated with the formation of the Zn vacancy-Related Defect (VZn). Comparing the transition energies of VZn obtained by the previous first principles calculation [Janotti and Van de Walle, Phys. Rev. B: Condens. Matter Mater. Phys., 2007, 76, 165202], the GL is associated with the transition from the conduction band to the e(−/2−) state of VZn and the DAP/FA emission involves the acceptor level e(0/−) of VZn.
Francis Chi-chung Ling - One of the best experts on this subject based on the ideXlab platform.
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Zn-vacancy Related Defects in ZnO grown by pulsed laser deposition
Oxide-based Materials and Devices VIII, 2017Co-Authors: Francis Chi-chung Ling, Caiqin Luo, Zilan Wang, Wolfgang Anwand, Andreas WagnerAbstract:Undoped and Ga-doped ZnO (002) films were grown c-sapphire using the pulsed laser deposition (PLD) method. Znvacancy Related Defects in the films were studied by different positron annihilation spectroscopy (PAS). These included Doppler broadening spectroscopy (DBS) employing a continuous monenergetic positron beam, and positron lifetime spectroscopy using a pulsed monoenergetic positron beam attached to an electron linear accelerator. Two kinds of Znvacancy Related Defects namely a monovacancy and a divacancy were identified in the films. In as-grown undoped samples grown with relatively low oxygen pressure P(O 2 )≤1.3 Pa, monovacancy is the dominant Zn-vacancy Related Defect. Annealing these samples at 900 o C induced Zn out-diffusion into the substrate and converted the monovacancy to divacancy. For the undoped samples grown with high P(O 2 )=5 Pa irrespective of the annealing temperature and the as-grown degenerate Ga-doped sample (n=10 20 cm -3 ), divacancy is the dominant Zn-vacancy Related Defect. The clustering of vacancy will be discussed.
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Zn-Vacancy Related Defects Identified in ZnO Films Grown by Pulsed Laser Deposition
Defect and Diffusion Forum, 2017Co-Authors: Francis Chi-chung Ling, Caiqin Luo, Zilan Wang, Wolfgang Anwand, Andreas WagnerAbstract:Undoped and Cu-doped ZnO grown on sapphire using pulsed laser deposition (PLD) were studied by positron annihilation spectroscopy (PAS), photoluminescence (PL), high-resolution transmission electron microscopy (HRTEM) and secondary ion mass spectroscopy (SIMS). In the undoped samples, two kinds of VZn-Related Defects, namely VZn1 and VZn2 are identified. VZn1 was identified in as-grown samples grown at relatively low substrate (~300 °C). After annealing at 900 °C, VZn-2, the green luminescence (GL) peaking at 2.47 eV and the near band edge (NBE) emission at 3.23 eV in the low temperature photoluminescence (LT-PL) were simultaneously introduced. Another kind of VZn-Related Defect is identified in the Cu-doped ZnO sample, and is tentatively assigned to the VZn decorated with the Cu.
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the zn vacancy Related green luminescence and donor acceptor pair emission in zno grown by pulsed laser deposition
RSC Advances, 2015Co-Authors: Zilan Wang, Francis Chi-chung Ling, Wolfgang Anwand, M. Younas, Shichen Su, Andreas WagnerAbstract:A low temperature (10 K) photoluminescence study shows that green luminescence (GL) peaking at 2.47 eV and near band edge (NBE) emission at 3.23 eV are introduced in undoped ZnO grown by pulsed laser deposition (PLD) after 900 °C annealing. The NBE emission exhibiting blue shift with increasing temperature is assigned to the transitions of the donor–acceptor-pair (DAP)/free-electron-to-acceptor (FA). Positron annihilation spectroscopy (PAS) study shows that the introduction of the GL is corRelated with the formation of the Zn vacancy-Related Defect (VZn). Comparing the transition energies of VZn obtained by the previous first principles calculation [Janotti and Van de Walle, Phys. Rev. B: Condens. Matter Mater. Phys., 2007, 76, 165202], the GL is associated with the transition from the conduction band to the e(−/2−) state of VZn and the DAP/FA emission involves the acceptor level e(0/−) of VZn.