Investigation of the electronic structure of the phosphorus-doped Si and Si02 : Si quantum dots by XPS and HREELS methods

The system of the nanocrystals of Si in the SiO2 matrix (SiO2 : Si) attracts a great amount of attention due to its ability for luminescence in the visible and near-IR range of spectrum. The influence of the P ion doping was investigated for the electronic structure of the Si single crystal and the SiO2 : Si nanocomposite. The P doping of SiO2 implanted with Si+ and post-annealed at T = 1000 deg C (2 h) results in the enhancement of the PL peak connected with the Si nanocrystals. Owing to the low concentration of Si nanocrystals in the SiO2 matrix, the peculiarities of the P influence on the Si electronic structure were investigated on model samples (Si single crystals with ion doping by P). The determination of the chemical state of the P impurity and the electronic structure of the P-doped Si and (SiO2 : Si) quantum dots was carried out using XPS and high-resolution electron energy loss spectroscopy (HREELS). The experimental density of the states (DOS) in the valence band and conduction band of the SiO2 : Si composite are in good agreement with the calculation of the local electronic structure around small Si inclusions in the SiO2 matrix by means of the LMTO (linear muffin-tin orbital) method.