Structural and optical properties of ～ 20 nm Ge nanoislands grown on Si（100） by radio frequency （rI） magnetron sputtering under varying annealing conditions are reported. Rapid thermal annealing at a temperature...Structural and optical properties of ～ 20 nm Ge nanoislands grown on Si（100） by radio frequency （rI） magnetron sputtering under varying annealing conditions are reported. Rapid thermal annealing at a temperature of 600 ℃ for 30 s, 90 s, and 120 s are performed to examine the influence of annealing time on the surface morphology and photoluminescence properties. X-ray diffraction spectra reveal prominent Ge and GeO2 peaks highly sensitive to the annealing time. Atomic force microscope micrographs of the as-grown sample show pyramidal nanoislands with relatively high-density （～ 10^11 cm^-2）. The nanoislands become dome-shaped upon annealing through a coarsening process mediated by Oswald ripening. The room temperature photoluminescence peaks for both as-grown （～ 3.29 eV） and annealed （～ 3.19 eV） samples consist of high intensity and broad emission, attributed to the effect of quantum confinement. The red shift （～ 0.10 eV） of the emission peak is attributed to the change in the size of the Ge nanoislands caused by annealing. Our easy fabrication method may contribute to the development of Ge nanostructure-based optoelectronics.展开更多
The Doppler spectral broadening resulted from non-stationary movement of target and radio-frequency inter-ference will decrease the veracity of target detection by high frequency ground wave(HFGW)radar.By displaying t...The Doppler spectral broadening resulted from non-stationary movement of target and radio-frequency inter-ference will decrease the veracity of target detection by high frequency ground wave(HFGW)radar.By displaying the change of signal energy on two dimensional time-frequency images based on time-frequency analysis,a new mathematical morphology method to distinguish target from nonlinear time-frequency curves is presented.The analyzed results from the measured data verify that with this new method the target can be detected correctly from wide Doppler spectrum.展开更多
Purpose: To show the follow-up of a case of vitelliform macular dystrophy with morphological and visual functional tests over an 8-year period.Methods:.Retrospective review of medical records..The morphological examin...Purpose: To show the follow-up of a case of vitelliform macular dystrophy with morphological and visual functional tests over an 8-year period.Methods:.Retrospective review of medical records..The morphological examination included color photography,.fluorescein angiography, and ocular coherence tomography(OCT).The visual functional tests included visual acuity, electro-oculogram(EOG) and multifocal electroretinography(mf ERG).The patient was observed for 8 years, from 2003 to 2011.Results:.During the follow-up,.the improvement of sensory retinal detachment and reduction of yellow-white deposit were observed with color photography and fluorescein angiography.OCT revealed a decrease in sensory retinal detachment and subretinal hyper-reflective deposits; both of these morphological changes were correspondent. Visual acuity was maintained throughout the follow-up..The Arden ratio of EOG was decreased. The amplitudes of mf ERG were decreased but slightly increased during the follow-up.Conclusion:.The retinal morphological changes and visual function slightly improved in this case of vitelliform maculopathy. The prognosis is good.展开更多
基金supported by the International Doctoral Fellowship (IDF), Ibnu Sina Institute for Fundamental Science Study and research grants of MoHE GUP. Vot No. 02H94 and 07J80
文摘Structural and optical properties of ～ 20 nm Ge nanoislands grown on Si（100） by radio frequency （rI） magnetron sputtering under varying annealing conditions are reported. Rapid thermal annealing at a temperature of 600 ℃ for 30 s, 90 s, and 120 s are performed to examine the influence of annealing time on the surface morphology and photoluminescence properties. X-ray diffraction spectra reveal prominent Ge and GeO2 peaks highly sensitive to the annealing time. Atomic force microscope micrographs of the as-grown sample show pyramidal nanoislands with relatively high-density （～ 10^11 cm^-2）. The nanoislands become dome-shaped upon annealing through a coarsening process mediated by Oswald ripening. The room temperature photoluminescence peaks for both as-grown （～ 3.29 eV） and annealed （～ 3.19 eV） samples consist of high intensity and broad emission, attributed to the effect of quantum confinement. The red shift （～ 0.10 eV） of the emission peak is attributed to the change in the size of the Ge nanoislands caused by annealing. Our easy fabrication method may contribute to the development of Ge nanostructure-based optoelectronics.
基金supported by the Hi-Tech Research and Development Program of China(No.2001AA631050).
文摘The Doppler spectral broadening resulted from non-stationary movement of target and radio-frequency inter-ference will decrease the veracity of target detection by high frequency ground wave(HFGW)radar.By displaying the change of signal energy on two dimensional time-frequency images based on time-frequency analysis,a new mathematical morphology method to distinguish target from nonlinear time-frequency curves is presented.The analyzed results from the measured data verify that with this new method the target can be detected correctly from wide Doppler spectrum.
文摘Purpose: To show the follow-up of a case of vitelliform macular dystrophy with morphological and visual functional tests over an 8-year period.Methods:.Retrospective review of medical records..The morphological examination included color photography,.fluorescein angiography, and ocular coherence tomography(OCT).The visual functional tests included visual acuity, electro-oculogram(EOG) and multifocal electroretinography(mf ERG).The patient was observed for 8 years, from 2003 to 2011.Results:.During the follow-up,.the improvement of sensory retinal detachment and reduction of yellow-white deposit were observed with color photography and fluorescein angiography.OCT revealed a decrease in sensory retinal detachment and subretinal hyper-reflective deposits; both of these morphological changes were correspondent. Visual acuity was maintained throughout the follow-up..The Arden ratio of EOG was decreased. The amplitudes of mf ERG were decreased but slightly increased during the follow-up.Conclusion:.The retinal morphological changes and visual function slightly improved in this case of vitelliform maculopathy. The prognosis is good.
