tailieunhanh - Báo cáo hóa học: " Si nanowires by a single-step metal-assisted chemical etching process on lithographically defined areas: formation kinetics"

Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Si nanowires by a single-step metal-assisted chemical etching process on lithographically defined areas: formation kinetics | Nassiopoulou et al. Nanoscale Research Letters 2011 6 597 http content 6 1 597 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Si nanowires by a single-step metal-assisted chemical etching process on lithographically defined areas formation kinetics Androula Galiouna Nassiopoulou Violetta Gianneta and Charalambos Katsogridakis Abstract In this paper we investigate the formation kinetics of Si nanowires SiNWs on lithographically defined areas using a single-step metal-assisted chemical etching process in an aqueous HF AgNO3 solution. We show that the etch rate of Si and consequently the SiNW length is much higher on the lithographically defined areas compared with that on the non-patterned areas. A comparative study of the etch rate in the two cases under the same experimental conditions showed that this effect is much more pronounced at the beginning of the etching process. Moreover it was found that in both cases the nanowire formation rate is linear with temperature in the range from 20 C to 50 C with almost the same activation energy as obtained from an Arrhenius plot eV in the case of non-patterned areas while eV in the case of lithographically patterned areas . The higher etch rate on lithographically defined areas is mainly attributed to Si surface modification during the photolithographic process. PACS 68 . Keywords Si nanowires metal-assisted chemical etching lithographically defined areas formation kinetics Introduction Si nanostructures such as quantum dots nanocrystals porous Si and Si nanowires SiNWs exhibit interesting properties 1-4 that are very different from their bulk counterparts and make them interesting for several applications. These properties include a diameter-dependent bandgap very-high-density electronic states an increased surface-to-volume ratio an enhanced exciton binding energy enhanced thermoelectric properties and increased surface scattering for electrons and .