Electron Excitation Memory Induced by Light Irradiation of Hydrogenated Si Nanocrystals Embedded in SiO2

We demonstrate an electron excitation effect in silicon nanocrystals (SiNCs) embedded in a SiO2 layer treated with hydrogen atoms for passivation of interface defects. Using electron spin resonance (ESR) measurements of quasi-conduction electrons (QCE) excited at lower temperatures, we observed the enhancement of the number of QCE in SiNCs by light irradiation. The electron excitation effect is retained at temperatures lower than 250 K after stopping the light irradiation. The dependence on the size of SiNCs and on excitation laser wavelength suggest that the main memory process is caused by photo-induced electron charging induced through electron excitation of interface states between SiNCs and SiO2.