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Computational simulation of the p-n doped silicon quantum dot

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  • For 60th birthday of S. Ya. Kilin

Abstract

Elongated crystalline silicon quantum dot (QD) codoped with aluminum and phosphorous together has been modeled with a formula of Si36Al1P1H42. The calculations of electronic structure are done by VASP software in the basis of plane waves, and valent electrons are treated explicitly while core electrons are described with pseudopotentials. Compared with undoped model, Si38H42, the results show the features in the electronic structure of the codoped QD of lowest unoccupied molecular orbital and highest occupied molecular orbital contributed by dopants, and transitions between those bands make contributions to many properties different from undoped model. The role of thermal motion of ions was also explored at (i) high and (ii) ambient temperatures. (i) At high temperature, the thermal motion of ions leads to the break of crystal structure. (ii) At ambient temperatures, the motion of ions facilitates the nonadiabatic couplings between electronic states. The relevant electronic dynamics also calculated with computed nonadiabatic couplings. This simulation predicts the charge transfer across p-n junction on atomistic scale. © 2012 Wiley Periodicals, Inc.

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