Investigation of the electronic structure of the phosphorus-doped Si and SiO2 : 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 = 1000degreesC (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. Copyright (C) 2004 John Wiley Sons, Ltd.