ELECTRONIC-PROPERTIES OF NANOSIZE SILICON-OXYGEN CLUSTERS

Optical absorption and light emission of oxygen incorporated small sil icon (Si14H24) clusters as a function of oxygen content were theoretic ally simulated by using a self-consistent semiempirical molecular orbi tal method (MNDO-PM3). Two different models of oxygen incorporation we re considered. Changes in the appropriate energies were traced when ox ygen atoms were introduced either to the cluster surface (OH-group pas sivation) or inside the cluster. An increase of the number of oxy gen atoms both at the surface and inside the cluster results in a decrease of the absorption energy with respect to the values typical for the c luster passivated only by hydrogen, while the emission energy appears to be influenced mainly by the incorporated oxygen content. There is a Stokes shift reaching the significant value of about 0.7 eV. It reduc es with the increase of the oxygen content down to a value of 0.2 eV i n the case of OH-group terminated clusters while it is almost constant for the oxygen incorporated ones.