Download or read book First-principles Calculations on the Electronic, Vibrational, and Optical Properties of Semiconductor Nanowires written by Li Yang and published by . This book was released on 2006 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the third part of my work, the electronic band structures of Si/Ge core-shell NWs are studied with first-principles calculations. The electronic states close to the band gap of NWs along the [110] direction are found to be confined within the core and the shell, respectively. Our calculated results show that the band offset between the core and shell electronic states are not only size dependent but also core-shell ratio dependent, which gives important corrections to those results from bulk heterojunctions and superlattices. The existence of band offsets makes it possible to dope impurities in the shell part of NWs while inject the carrier to the core part, or vise versa. This novel doping mechanism avoids the scattering process induced by doped impurities and gives hope to the high-speed NW devices. Finally, based on our calculations, the optimal doping strategy is proposed.