SHORT-WAVELENGTH PHOTOLUMINESCENCE OF SIO2 LAYERS IMPLANTED WITH HIGH-DOSES OF SI+, GE+, AND AR+ IONS

The short-wavelength (400-700 nm) photoluminescence (PL) spectra of Si O2 layers implanted with Si+, Ge+, and Ar+ ions in the dose range 3.2x 10(16)-1.2x10(17) cm(-2) are compared. After Ar+ implantation an extre mely weak luminescence, which vanishes completely after annealing for 30 min at 400 degrees C or 20 ms at 1050 degrees C, was observed. Afte r implantation of group-IV elements the luminescence intensities were 1 to 2 orders of magnitude higher, and the luminescence remained not o nly with annealings but it could also increase. The dose and heating d ependences of the luminescence show that it is due to the formation of impurity clusters and this process is more likely to be of a percolat ion than a diffusion character. For both group-IV impurities an intens e blue band and a weaker band in the orange part of the spectrum were observed immediately after implantation. The ratio of the excitation a nd emission energies of the blue luminescence is characteristic of oxy gen vacancies in SiO2; its properties are determined by the direct int eraction of group-IV atoms. On this basis it is believed that the cent ers of blue PL are chains of Si (or Ge) atoms embedded in SiO2. The or ange luminescence remained after annealings only in the case of Si+ im plantation. This is attributed directly to the nonphase precipitates o f Si in the form of strongly developed nanometer-size clusters. (C) 19 98 American Institute of Physics.