Density functional theory study on the B doping and B/P codoping of Si nanocrystals embedded in SiO2

Abstract

Doping silicon nanocrystals (Si NCs) embedded in silicon dioxide ($\mathrm{Si}{\mathrm{O}}_{2}$) with boron (B) and phosphorus (P) is a promising way of tuning the properties of Si NCs. Here we take advantage of density functional theory to investigate the dependence of the structural and electronic properties of Si NCs embedded in $\mathrm{Si}{\mathrm{O}}_{2}$ on the doping of B and P. The locations and energy-level schemes are examined for singularly B-doped or B/P-codoped Si NCs embedded in $\mathrm{Si}{\mathrm{O}}_{2}$ with a perfect or defective Si/$\mathrm{Si}{\mathrm{O}}_{2}$ interface at which a Si dangling bond exists. A dangling bond plays an important role in the doping of Si NCs with B or B/P. The doping behavior of B in Si NCs embedded in $\mathrm{Si}{\mathrm{O}}_{2}$ vastly differs from that of P. The electronic structure of a B/P-codoped Si NC largely depends on the distribution of the dopants in the NC.