We describe the fabrication of silicon micro-hemispheres by adopting the conventional laser ablation of single crystalline silicon in the vacuum condition without using any catalysts or additives. The highly oriented ...We describe the fabrication of silicon micro-hemispheres by adopting the conventional laser ablation of single crystalline silicon in the vacuum condition without using any catalysts or additives. The highly oriented structures of silicon micro-hemispheres exhibit many periodic nanoscale rings along their outer surfaces. We consider that the self-organized growth of silicon micro-structures is highly dependent on the laser intensity and background air medium. The difference between these surface modifications is attributed to the amount of laser energy deposited in the silicon material and the consequent cooling velocity.展开更多
Face-centered-cubic(fcc) structure silicon nanoparticles(Si-nps) are synthesized by using nanosecond pulse excimer laser ablation of Si target in Ar ambient.The nonequilibrium environment caused by the plume confined ...Face-centered-cubic(fcc) structure silicon nanoparticles(Si-nps) are synthesized by using nanosecond pulse excimer laser ablation of Si target in Ar ambient.The nonequilibrium environment caused by the plume confined in argon ambient gas is responsible for the formation of fcc Si-nps.Photoluminescence(PL),transmission electron microscopy,and X-ray photoelectron spectroscopy are used to characterize these Si-nps.Broad PL spectrum is obtained with a double-peak at 403 and 503 nm by an exciting laser of 325 nm.After exposure to air for 60 days,air oxidation over time causes a clear blue-shift in green PL peak from 503 to 484 nm and no shift in violet PL peak of 403 nm.The present results indicate that the peak of 503 nm and blue-shift from 503 to 484 nm are attributed to the band-to-band recombination of quantum confinement model,while the violet PL peak of 403 nm is due to the recombination of electron transition from interface states of suboxides.展开更多
A series of ablation experiments on silicon surface by femtosecond laser system of 775 nm and 150 fs duration pulses were carried out.The morphological characteristics and the associated effect in the ablation were te...A series of ablation experiments on silicon surface by femtosecond laser system of 775 nm and 150 fs duration pulses were carried out.The morphological characteristics and the associated effect in the ablation were tested by atomic force microscope(AFM),scanning electron microscope(SEM),focused ion beam(FIB),and the optic microscope.The single pulse threshold can be obtained directly.For the multiple pulses,the ablation threshold varies with the number of pulses applied to the surface due to the incubation effect.By analyzing the experimental data,the thresholds of laser fluences under various laser pulse numbers were obtained,and the relationships between ablation area and laser energy and laser pulse number were concluded.Meanwhile,the periodic ripple structure on silicon surface was found.Under the condition of certain laser power,the number of laser pulse can influence the formation of ripples.展开更多
采用脉冲激光烧蚀法,以多晶3C-SiC陶瓷片为靶材,制备了悬浮于去离子水中的非晶SiC纳米颗粒。利用透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)、傅里叶变换红外吸收光谱(FTIR)、紫外可见吸收光谱(UV-Vis)和光致发光谱(PL)等测试...采用脉冲激光烧蚀法,以多晶3C-SiC陶瓷片为靶材,制备了悬浮于去离子水中的非晶SiC纳米颗粒。利用透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)、傅里叶变换红外吸收光谱(FTIR)、紫外可见吸收光谱(UV-Vis)和光致发光谱(PL)等测试手段对其形貌、结构和光学性质进行了分析。结果表明:这些纳米颗粒由大量的非晶SiC构成,粒径在8~9 nm,光学带隙为3.28 e V;样品表现出较强的光致发光,发光峰位于415 nm处,这主要是由于量子限制效应造成的。展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos.11105085 and 11075097)the Excellent Youth and Middle Age Scientists Fund of Shandong Province,China (Grant No.BS2012CL024)the Project of Higher Educational Science and Technology Program of Shandong Province,China (Grant No.J12LA51)
文摘We describe the fabrication of silicon micro-hemispheres by adopting the conventional laser ablation of single crystalline silicon in the vacuum condition without using any catalysts or additives. The highly oriented structures of silicon micro-hemispheres exhibit many periodic nanoscale rings along their outer surfaces. We consider that the self-organized growth of silicon micro-structures is highly dependent on the laser intensity and background air medium. The difference between these surface modifications is attributed to the amount of laser energy deposited in the silicon material and the consequent cooling velocity.
基金supported by the National Natural Science Foundation for Distinguished Young Scholars of China (Grant No 50902010) and Dow Corning Corp
文摘Face-centered-cubic(fcc) structure silicon nanoparticles(Si-nps) are synthesized by using nanosecond pulse excimer laser ablation of Si target in Ar ambient.The nonequilibrium environment caused by the plume confined in argon ambient gas is responsible for the formation of fcc Si-nps.Photoluminescence(PL),transmission electron microscopy,and X-ray photoelectron spectroscopy are used to characterize these Si-nps.Broad PL spectrum is obtained with a double-peak at 403 and 503 nm by an exciting laser of 325 nm.After exposure to air for 60 days,air oxidation over time causes a clear blue-shift in green PL peak from 503 to 484 nm and no shift in violet PL peak of 403 nm.The present results indicate that the peak of 503 nm and blue-shift from 503 to 484 nm are attributed to the band-to-band recombination of quantum confinement model,while the violet PL peak of 403 nm is due to the recombination of electron transition from interface states of suboxides.
基金Supported by National High Technology Research and Development Program of China ("863"Program) (No.2006AA04Z327)National Natural Science Foundation of China (No.60372006)Program for New Century Excellent Talents in University
文摘A series of ablation experiments on silicon surface by femtosecond laser system of 775 nm and 150 fs duration pulses were carried out.The morphological characteristics and the associated effect in the ablation were tested by atomic force microscope(AFM),scanning electron microscope(SEM),focused ion beam(FIB),and the optic microscope.The single pulse threshold can be obtained directly.For the multiple pulses,the ablation threshold varies with the number of pulses applied to the surface due to the incubation effect.By analyzing the experimental data,the thresholds of laser fluences under various laser pulse numbers were obtained,and the relationships between ablation area and laser energy and laser pulse number were concluded.Meanwhile,the periodic ripple structure on silicon surface was found.Under the condition of certain laser power,the number of laser pulse can influence the formation of ripples.
文摘采用脉冲激光烧蚀法,以多晶3C-SiC陶瓷片为靶材,制备了悬浮于去离子水中的非晶SiC纳米颗粒。利用透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)、傅里叶变换红外吸收光谱(FTIR)、紫外可见吸收光谱(UV-Vis)和光致发光谱(PL)等测试手段对其形貌、结构和光学性质进行了分析。结果表明:这些纳米颗粒由大量的非晶SiC构成,粒径在8~9 nm,光学带隙为3.28 e V;样品表现出较强的光致发光,发光峰位于415 nm处,这主要是由于量子限制效应造成的。
