凝聚态物理报告课件.ppt

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1、,Anisotropy in stability andYoungs modulus ofhydrogenatedP+trsilIcon nanowires,owe team,StatementThis article is available online on 31December 2007Because the article published earlierNano technology in recent years with newdevelopment,may appear new theory orexperiment we did not study about it so

2、 thisdiscussion is limited to this article,contentBackground The research contentThe significance of this research,BackgroundRecent experiments have shown that smallsilicon nanowires siNWs)with various sizes andcrystallographic orientations can be successfullysynthesized.it was possible to fabricate

3、 singlecrystalline si nanowires with diameters as smallas1 nm and lengths of a few tens ofmicrometersSUPERCOURSE CHINA,BackgroundHow to get the materialsWith the oxide-assisted growth methodsthe synthesized nanowires usually consist of acrystalline core surrounded by an outer oxidelayer.Further remo

4、val of the oxide layer byacid treatment may lead to hydrogen-passivated Si nanowires as thin as 1nm 4SUPERCOURSE CHINA,The research contentwe investigate energetic relative sta bilityand mechanical properties of the hydrogenpassivated siNWs with various diameters andgrowth directions using first-pri

5、nciplesmethods To compare the physical propertiesand to understand the possible reason for apreferential growth direction,nanowiresgrown along the 100,110,111 and 112crystallographic orientations have beenstudied,Nanowires with variouscrystallographicorientationsIn all the sinws consideredthe dangli

6、ng bonds on thesurface are fullyterminated with h atomsso that each siatom lying on the8含爸nanowire surface istetrahedrally coordnated舍争lIlI,Research methodsPerform Geometry optimizations using DFTimplemented in the dMol packageChose All-electron treatment and double numericabasis including p-polarization function(DNP)The exchange-correlation interaction was treatedwithin the generalized gradient approximation(GGA)with the functional parameterized,