Structural and optical properties of semiconducting microcrystallite-doped SiO2 glass films prepared by rf-sputtering

摘要

Abstract: Semiconducting microcrystallite-doped silica-glass films were prepared by the rf-magnetron sputtering technique using a composite target consisting of a SiO$-2$/ plate and semiconductor chips. The semiconductors doped were GaAs, In$-x$/Ga$-1$MIN@x$/As, CdSe, CdTe, CuCl, Si, Ge, and so on. The structure of those microcrystallites (MCs) was investigated with high- resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD), small angle x-ray scattering (SAXS), and EXAFS. The MCs had a spherical configuration 20 to 100 angstroms in diameter. The average size of the MCs was completely controlled by the deposition condition and the postannealing time. Clear lattice images observed in the HRTEM photograph suggested that the MCs had a similar structure compared with the bulk crystal. The blue shift of the optical absorption edge could be observed for all of the samples. This seemed to probe the quantum size effect. Concentration of the MCs estimated by x-ray photoelectron spectroscopy (XPS) was more than 10 mol%. This value was one or two orders in magnitude larger than that of SDGs prepared by the melting and quenching method. The results of EXAFS measurements suggest that the microscopic structure in the MCs was almost the same as that of bulk crystals except for their surface. By SAXS measurements, an average interparticle distance in the microcrystallites could be estimated for the first time. Waveguiding behavior was also reported for the sputtered CdSe microcrystallite-doped glass film.!