tailieunhanh - Báo cáo hóa học: " On the nature of the stretched exponential photoluminescence decay for silicon nanocrystals"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: On the nature of the stretched exponential photoluminescence decay for silicon nanocrystals | Zatryb et al. Nanoscale Research Letters 2011 6 106 http content 6 1 106 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access On the nature of the stretched exponential photoluminescence decay for silicon nanocrystals 1 1 12 2 G Zatryb A Podhorodecki J Misiewicz J Cardin F Gourbilleau Abstract The influence of hydrogen rate on optical properties of silicon nanocrystals deposited by sputtering method was studied by means of time-resolved photoluminescence spectroscopy as well as transmission and reflection measurements. It was found that photoluminescence decay is strongly non-single exponential and can be described by the stretched exponential function. It was also shown that effective decay rate probability density function may be recovered by means of Stehfest algorithm. Moreover it was proposed that the observed broadening of obtained decay rate distributions reflects the disorder in the samples. Introduction The discovery of visible photoluminescence PL from porous silicon and then silicon nanocrystals Si-NCs has stimulated a great deal of interest in this material mainly due to a number of promising potential applications like for instance light emitting diodes 1 or silicon-based lasers 2 . Although the quantum efficiency of Si-NCs emission gives hope for future device applications it remains low compared to the direct band gap III-V or II-VI materials. It is partially due to technological problems with fabrication of defect-free and structurally uniform Si-NCs samples where nonradiative recombination sites do not play a key role in the emission process. From this point of view the improvement of Si-NCs emission quantum efficiency remains an important challenge for further optoelectronic applications. Thus any experimental tool that leads to information about non-uniformity of Si-NCs structures and its influence on emission properties is valuable. The optical properties of Si-NCs can be investigated by means of