Model of photoluminescence from ion-synthesized silicon nanocrystal arrays embedded in a silicon dioxide matrix

A four-level model of photoluminescence from Si nanocrystal arrays embedded in a SiO 2 matrix is suggested. The model allows for thermally activated transitions between singlet and triplet levels in the exchange-split energy state of an exciton in an excited silicon nanocrystal. An expression is derived for the temperature dependence of the intensity of photoluminescence monochromatic components. A correlation is found between the amount of splitting and the emitted photon energy by comparing model data with our experimental data for ion-synthesized Si nanocrystals in a SiO 2 matrix. The model explains the finiteness of the photoluminescence intensity at temperatures close to 0 K and the nonmonotonicity of the temperature run of the intensity.