EFTEM-HRTEM characterization of Er-doped silicon nanocrystal-based oxides/nitrides for MOS light emitting devices

Abstract

Er-doped silicon nanocrystal-based oxides/nitrides have been investigated. These layers are grown between a polycrystalline silicon electrode and a monocrystalline silicon substrate to allow electrical injection. Energy Filtered (EF-) and High Resolution (HR-) TEM characterization has been performed to provide microscopic insight onto the macroscopic optoelectronic properties of the samples. Evident Er-clustering has been observed in silicon dioxides but not in silicon nitrides, suggesting a better Er solubility and local environment when nitrogen is incorporated. Silicon nanocrystals have been observed in silicon-rich nitride layers, as expected, but also in a region close to the silicon dioxide-polysilicon interface in a layer with no nitrogen or Si excesses. This unexpected Si clusterization has been attributed to Si diffusion from the polycrystalline silicon electrode into the silicon dioxide as a consequence of the annealing treatment. The structural characterization carried out by HRTEM and EFTEM has been correlated with the optoelectronic properties of the devices.