A new low-energy negative-ion induced luminescence setup was recently developed at the injector of the GIC4117 2 × 1.7 MV Tandem accelerator in Beijing Normal University. In situ luminescence measurements are per...A new low-energy negative-ion induced luminescence setup was recently developed at the injector of the GIC4117 2 × 1.7 MV Tandem accelerator in Beijing Normal University. In situ luminescence measurements are performed on silica glass by using 20key H ions at room temperature. Gauss fitting of the spectra revealed six overlapping components at about 2.7eV, 2.4eV, 1.geV, 1.8eV, 4.2eV, and 3.6eV, which except for the new observed emission band at 3.6eV are assigned to the creation of type lI oxygen-deficient centers, E＇ centers, non-bridging oxygen hole centers with different precursor states, and type-I oxygen-deficient centers. The fitted results of the saturation concentration show that self-trapped exciton recombination at type-lI oxygen-deficient centers is the main luminescence emission process. The evolution of the luminescence intensity and full width at half maximums as a function of ion fluence is also discussed. It is found that the number of recombination centers reaches its maximum at lower Huence, and the area ratio between blue bands and red bands is much lower than that under high energy H＋ ion irradiation.展开更多
The ionoluminescence （IL） spectra of a ZnO single crystal irradiated with 2.5？MeV H＋＋ ions reveal that its intensity decreases with increasing the ion fluence, which indicates that the concentration of luminescen...The ionoluminescence （IL） spectra of a ZnO single crystal irradiated with 2.5？MeV H＋＋ ions reveal that its intensity decreases with increasing the ion fluence, which indicates that the concentration of luminescence centers decreases with irradiation. The Gaussian decomposition results of the ZnO IL spectrum with a fluence of 1.77×10^11ions/cm^2 show that the spectrum is a superposition of energy levels centered at 1.75eV, 2.10eV, 3.12eV and 3.20eV. The four peaks are associated with electronic transitions from CB to VZnZn, CB to Oii, Znii to VB and the decay of self-trapped excitons, respectively. The results of single-exponential fitting demonstrate that different luminescent centers have different radiation resistance, which may explain why the emission decreases more slowly in the NBE band than in the DBE band. The agglomeration of larger point clusters accounts for the decrease in the concentration of luminescence centers and the increase in the concentration of non-luminescence centers, which indicates that the defect clusters induced by ion implantation act as nonradiative recombination centers and suppress light emission. The results of the photoluminescence spectra of a virgin ZnO single crystal and a ZnO single crystal irradiated with a fluence of 3.4××10^14ions/cm^2 show that compared with the virgin ZnO, the emission intensity of irradiated ZnO decreases by nearly two orders of magnitude, which demonstrates that the irradiation effect reduces radiative recombination and enhances nonradiative recombination. The conclusions of photoluminescence are consistent with the IL results.展开更多
Negative ion-beam-induced luminescence (IBIL) measurements of a pure LiF crystal using 20 keV are performed to monitor the formation and annihilation of luminescence centers during ion irradiation. Several emission ba...Negative ion-beam-induced luminescence (IBIL) measurements of a pure LiF crystal using 20 keV are performed to monitor the formation and annihilation of luminescence centers during ion irradiation. Several emission bands are observed in the IBIL spectra and the evolvement mechanisms of the corresponding centers are identified. The difference between the IBIL measurements using positive ions and negative ions is that the intensities of luminescence centers can reach the maxima at lower fluences under negative-ion irradiation due to free charge accumulation.展开更多
文摘A new low-energy negative-ion induced luminescence setup was recently developed at the injector of the GIC4117 2 × 1.7 MV Tandem accelerator in Beijing Normal University. In situ luminescence measurements are performed on silica glass by using 20key H ions at room temperature. Gauss fitting of the spectra revealed six overlapping components at about 2.7eV, 2.4eV, 1.geV, 1.8eV, 4.2eV, and 3.6eV, which except for the new observed emission band at 3.6eV are assigned to the creation of type lI oxygen-deficient centers, E＇ centers, non-bridging oxygen hole centers with different precursor states, and type-I oxygen-deficient centers. The fitted results of the saturation concentration show that self-trapped exciton recombination at type-lI oxygen-deficient centers is the main luminescence emission process. The evolution of the luminescence intensity and full width at half maximums as a function of ion fluence is also discussed. It is found that the number of recombination centers reaches its maximum at lower Huence, and the area ratio between blue bands and red bands is much lower than that under high energy H＋ ion irradiation.
文摘The ionoluminescence （IL） spectra of a ZnO single crystal irradiated with 2.5？MeV H＋＋ ions reveal that its intensity decreases with increasing the ion fluence, which indicates that the concentration of luminescence centers decreases with irradiation. The Gaussian decomposition results of the ZnO IL spectrum with a fluence of 1.77×10^11ions/cm^2 show that the spectrum is a superposition of energy levels centered at 1.75eV, 2.10eV, 3.12eV and 3.20eV. The four peaks are associated with electronic transitions from CB to VZnZn, CB to Oii, Znii to VB and the decay of self-trapped excitons, respectively. The results of single-exponential fitting demonstrate that different luminescent centers have different radiation resistance, which may explain why the emission decreases more slowly in the NBE band than in the DBE band. The agglomeration of larger point clusters accounts for the decrease in the concentration of luminescence centers and the increase in the concentration of non-luminescence centers, which indicates that the defect clusters induced by ion implantation act as nonradiative recombination centers and suppress light emission. The results of the photoluminescence spectra of a virgin ZnO single crystal and a ZnO single crystal irradiated with a fluence of 3.4××10^14ions/cm^2 show that compared with the virgin ZnO, the emission intensity of irradiated ZnO decreases by nearly two orders of magnitude, which demonstrates that the irradiation effect reduces radiative recombination and enhances nonradiative recombination. The conclusions of photoluminescence are consistent with the IL results.
文摘Negative ion-beam-induced luminescence (IBIL) measurements of a pure LiF crystal using 20 keV are performed to monitor the formation and annihilation of luminescence centers during ion irradiation. Several emission bands are observed in the IBIL spectra and the evolvement mechanisms of the corresponding centers are identified. The difference between the IBIL measurements using positive ions and negative ions is that the intensities of luminescence centers can reach the maxima at lower fluences under negative-ion irradiation due to free charge accumulation.
