Study of the dielectric properties near the band gap of semiconductors by Valence EELS. Part II : nanoparticles embedded in SiO2
Sylvie SCHAMM 1, G. Zanchi 1, A. Perez-Rodriguez 2, R. Rodriguez 3
e-mail: schamm@cemes.fr
1 CEMES-CNRS, 29, rue Jeanne Marvig, BP4347, 31055 Toulouse cedex 04, France
2 Electronics Department, University of Barcelona, carrer Marti i Franqués 1, 08028 Barcelona, Spain
3 Asociacion de la Industria Navarra (AIN) Cordovilla, Pamplona, Spain
Compound nanoparticles ion beam synthesized in SiO2 are potentially interesting for optoelectronic applications such as electroluminescent devices compatible with the CMOS technology. In particular, GaN nanoparticles embedded in SiO2 are very interesting for the fabrication of optoelectronic devices emitting in the blue and UV spectral range.
Thermally grown 400 nm thick amorphous SiO2 films on (100) oriented silicon wafers have been co-implanted with Si (130 keV, 10^17 cm-2 and 60keV, 5x10^16 cm-2), Ga (250 keV, 5x10^16 cm-2) and N(35 keV, 5x10^16 cm-2 and 75 keV, 10^17 cm-2) at room temperature. The samples have been further annealed under flowing NH3 atmosphere at 900°C in a rapid thermal annealing furnace during 15 minutes.
The formation of amorphous nanoparticles with 3 nm of mean diameter have been observed by Transmission Electron Microscopy.
In order to determine the nature of the nanoparticles, ELNES of the N-K edge corresponding to these particles are compared to the one of a GaN reference sample.
The imaginary part of the dielectric functions in the region of the band gap (cf part I) corresponding to the nanoparticles and to the bulk GaN reference sample are compared in order to investigate the effect of the reduction in size of the material.