کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5358325 | 1503650 | 2014 | 9 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Incubation and nanostructure formation on n- and p-type Si(1Â 0Â 0) and Si(1Â 1Â 1) at various doping levels induced by sub-nanojoule femto- and picosecond near-infrared laser pulses
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
N- and p-doped Si(1Â 0Â 0) and Si(1Â 1Â 1) surfaces with dopant concentrations of 2Â ÃÂ 1014-1Â ÃÂ 1019Â cmâ3 were irradiated by tightly focused 85-MHz repetition rate Ti:sapphire laser light (central wavelength 800Â nm, bandwidth 120Â nm) at pulse durations of 12Â fs to 1.6Â ps. Dependent on pulse peak intensity and exposure time nanorifts, ripples of period 130Â nm as well as sponge-like randomly nanoporous surface structures were generated with water immersion and, thereafter, laid bare by etching off aggregated oxide nanoparticles. The same structure types emerged in air or water with transform-limited 100-fs pulses. At a pulse length of 12Â fs pronounced incubation occurred with incubation coefficients SÂ =Â 0.66-0.85, whereas incubation was diminished for picosecond pulses (SÂ >Â 0.95). The ablation threshold strongly rose with dopant concentration. At similar doping level it was higher for n-type than for p-type samples and for Si(1Â 0Â 0) compared to Si(1Â 1Â 1) surfaces. These observations are attributed to laser-induced defect states in the bandgap which participate in photoexcitation, deactivation of dopants by complex formation, and different densities of interface states at the boundary with the ultrathin native silicon dioxide surface layer. The threshold increase with pulse length revealed predominant single-photon excitation as well as multiphoton absorption.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Applied Surface Science - Volume 314, 30 September 2014, Pages 21-29
Journal: Applied Surface Science - Volume 314, 30 September 2014, Pages 21-29
نویسندگان
M. Schüle, M. Afshar, D. Feili, H. Seidel, K. König, M. Straub,