High energy electron-beam irradiation effects in Si-SiO_x structures

摘要

Homogeneous SiO_x films (x=1.3, 200 nm and 1000 nm thick) and composite a-Si-SiO_y films (y~ 1.80) containing amorphous Si nanoparticles have been prepared on crystalline (c-Si) substrate. A part of the films was irradiated at temperature below 50 °C by 20 MeV electrons with two different fluences (7.2×10~(14) and 1.44×l0~(15) el.cm~(-2)). Atomic force microscopy (AFM), Raman spectroscopy and capacitance (conductance) - voltage (C(G)-V) measurements on Al/c-Si/SiO_x/Al or Al/c-Si/(a-Si-SiO_y)/Al structures were used to get information about the irradiation induced changes in the surface morphology, the phase composition in the film bulk and at the Si-SiO_x interface. The AFM results show that the electron irradiation decreases the film surface roughness of the films annealed at 250 °C. The Raman scattering data imply appearance of amorphous silicon phase and some structural changes in the oxide matrix of the homogeneous SiO_x films. In the composite films electron beam stimulated decrease of the defects at the a-Si/SiO_y interface has been assumed. The initial C(G)-V results speak about electron induced formation of electrically active defects in the SiO_y matrix of the composite films.