Tailored Nanoheterojunctions for Optimized Light Emission

Tianshu Li, Francois Gygi, and Giulia Galli

Phys. Rev. Lett. 107, 206805 – Published 8 November 2011

Abstract

We present coupled classical and quantum simulations of 1 to 2 nm Si nanocrystals (NCs) embedded in amorphous ${SiO}_{2}$ and we show that by tuning the density of the oxide matrix one may change the relative alignment of Si NC and ${SiO}_{2}$ electronic states at the interface. We find that interfacial strain plays a key role in determining the variation of the nanaoparticle gap as a function of size, as well as of conduction band offsets with the oxide. In particular, our results show that it is the variation of the valence band offset with size that is responsible for the gap change. Our findings suggest that the elastic properties of the embedding matrix may be tuned to tailor the energy levels of small Si NCs so as to optimize their performance in optoelectronic devices and solar cells.

Received 18 May 2011

DOI:https://doi.org/10.1103/PhysRevLett.107.206805

Authors & Affiliations

Tianshu Li^1,*, Francois Gygi^2,3, and Giulia Galli^4,5

¹Department of Civil and Environmental Engineering, George Washington University, Washington, D.C. 20052, USA
²Department of Applied Science, University of California, Davis, California 95616, USA
³Department of Computer Science, University of California, Davis, California 95616, USA
⁴Department of Chemistry, University of California, Davis, California 95616, USA
⁵Department of Physics, University of California, Davis, California 95616, USA