Anti-Stokes luminescence tail in porous Si

The anti-Stokes luminescence tail of resonantly excited porous Si and its temperature evolution have been observed in the energy range of 0.2 eV from the excitation energy. The activation energy calculated from the Arrhenius plot of the anti-Stokes luminescence intensity agrees with the anti-Stokes shift. This means that the intensity Iasl(hν,Eexc,T) of the anti-Stokes luminescence with photon energy hν from the porous Si excited with light of energy Eexc at temperature T can be described by Iasl(hν,Eexc,T)=f(hν,Eexc) exp{−(hν−Eexc)/kT}, where hν>Eexc. The pre-exponential factor f(hν,Eexc) is related to the density of states of an electron–hole pair in an Si nanostructure with a bandgap Eexc. The behavior of f(hν,Eexc) has been found to agree with the low photon energy part of the excitation spectrum of the luminescence.