Enhanced quantum confinement in tensile-strained silicon nanocrystals embedded in silicon nitride

Here, we report that the tensile strain in silicon nanocrystals embedded in silicon nitride significantly changes the size-dependent evolution of the conduction and valence energy levels, compared with strain-free silicon nanocrystals. Using capacitance spectroscopy, the quantum-confined energy shifts in the conduction and valence levels were identified as ΔEC(eV) = 11.7/d2, and ΔEV(eV) = −4.5/d2, where d is the mean diameter of the silicon nanocrystals in nanometers. These findings indicated that the tensile strain in the silicon nanocrystals significantly increased the quantum confinement, by a factor of 3.3 in the conduction levels, and by a factor of 1.8 in the valence levels.