Büyüklük ve şekil modülasyonlu silisyum tabanlı nanotel süperörgüler

Mechanical properties, atomic and energy band structures of bare and hydrogen passivated SinGen nanowire superlattices have been investigated by using first principles pseudopotential plane wave method. Undoped, tetrahedral Si and Ge nanowire segments join pseudomorphically and can form superlattice with atomically sharp interface. Upon heterostructure formation, superlattice electronic states form subbands in momentum space. Band lineups of Si and Ge zones result in multiple quantum wells, where speciic states at the band edges and in band continua are con¯ned. The electronic structure of the nanowire superlattice depends on the length and cross section geometry of constituent Si and Ge segments. Also we showed that hydrogen saturated silicon nanowires of different diameters having di®erent band gaps can form stable junctions. Superlatticesformed by the periodically repeated junctions of silicon nanowire segments having different lengths and diameters exhibit electronic states which can be confined in regions having either narrow or wide parts of superlattice. A point defect, suchas a missing atom or substitutional impurities with localized states near band edges can make modulation doping possible. Since bare Si and Ge nanowires bare metallic and the band gaps of hydrogenated ones varies with the diameter, these superlattices other numerous options for multiple quantum well devices with their leads made from the constituent metallic nanowires. Finally, we have considered the junction between bare and hydrogenated nanowires to realise metal-semiconductor heterostructure. We have treated this heterostructure within the supercell geometry and deduced the formation of Schottky barrier. We haveshown that Si and Ge nanowires can bring about a novel concept in nanocircuit, where interconnects, devices etc are produced on a single rode.