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Abstract:
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Nanostructures often possess unique properties , which may lead to the development of new microelectronic and optoelectronic devices . They also provide an opportunity to test fundamental quantum mechanical concepts such as the role of quantum confinement . Considerable effort has been made to understand the electronic and structural properties of nanostructures , but many fundamental issues remain . In this work , the electronic and structural properties of nanostructures are examined using several new computational methods . The effect of dimensional confinement on quantum levels is investigated for hydrogenated Ge <110 > using the plane -wave density -functional -theory pseudopotential method . We present a real -space pseudopotential method for calculating the electronic structure of one -dimensional periodic systems such as nanowires . As an application of this method , we examine H -passivated Si nanowires . The band structure and heat of formation of the Si nanowires are presented and compared to plane wave methods . Our method is able to offer the same accuracy as the traditional plane wave methods , but offers a number of computational advantages such as the ability to handle large systems and a better ease of implementation for highly parallel platforms .
Doping is important to many potential applications of nano -regime semiconductors . A series of first -principles studies are conducted on the P -doped Si <110 > nanowires by the real -space pseudopotential methods . Nanowires of varied sizes and different doping positions are investigated . We calculate the binding energies of P atoms , band gaps of the wires , energetics of P atoms in different doping positions and core -level shift of P atoms . Defect wave functions of P atoms are also analyzed . In addition , we study the electronic properties of phosphorus -doped silicon <111 > nanofilms using the real -space pseudopotential method . Nanofilms with varied sizes and different doping positions are investigated . We calculate the binding energies of P atoms , band gaps of the films , and energetics of P atoms in different doping positions . Quantum confinement effects are compared with P -doped Si nanocrystals and as well as nanowires . We simulate the nanofilm STM images with P defects in varied film depths , and make a comparison with the experimental measurement . |