ENHANCED CRYSTALLIZATION OF AMORPHOUS SI CONTAINING HYDROGEN WITHOUT OXYGEN DURING ION-BEAM IRRADIATION AT 310-DEGREES-C AND DURING FURNACEANNEALING BELOW 450-DEGREES-C
J. Nakata, ENHANCED CRYSTALLIZATION OF AMORPHOUS SI CONTAINING HYDROGEN WITHOUT OXYGEN DURING ION-BEAM IRRADIATION AT 310-DEGREES-C AND DURING FURNACEANNEALING BELOW 450-DEGREES-C, Journal of applied physics, 82(11), 1997, pp. 5433-5445
The epitaxial crystallization rates of amorphous Si layers on crystall
ine Si substrates containing a considerable number of hydrogen atoms a
re markedly increased in the absence of oxygen atoms. This enhanced cr
ystallization occurs both during 1-MeV Xe-ion-beam irradiation at 310
degrees C and during furnace annealing in vacuum at temperatures below
450 degrees C. Implantation-amorphized crystal Si layers epitaxially
grown on the (100)-crystalline Si substrates by ultrahigh vacuum chemi
cal vapor deposition (UHV-CVD) are epitaxially crystallized by furnace
annealing in vacuum at temperatures below 450 degrees C. Implantation
-amorphized bulk-crystal Si substrates, however, are not entirely crys
tallized by the same low-temperature annealing. Nanometer-scale microc
rystallites, remaining at the near-surface region in the amorphous Si
layer after 80-keV phosphorus implantation into the UHV-CVD epitaxial
Si layer, grow three-dimensional during 1-MeV Xe-ion-beam irradiation
at 310 degrees C, but not during furnace annealing at 600 degrees C in
dry Ar ambient. This three-dimensional crystal growth does not occur
in implantation-amorphized bulk-crystal Si substrates, even during 1-M
eV Xe-ion-beam irradiation. Amorphous Si layers directly deposited by
low-pressure CVD (LP-CVD) are crystallized epitaxially by 1-MeV Xe-ion
-beam irradiation at 310 degrees C. The crystallization rate of the LP
-CVD sample heated in the deposition furnace after evacuation is twice
as high as that of the sample heated before evacuation. All these res
ults are explained consistently by the presence of a considerable amou
nt of hydrogen in polyhydride states in the amorphous Si layers in the
absence of oxygen. It is suggested that the mechanism of low-temperat
ure crystalline of amorphous Si containing hydrogen in polyhydride sta
tes closely related, in terms of vacant spaces and dangling-bonds, to
the mechanism of ion-beam-induced epitaxial crystallization. (C) 1997
American Institute of Physics.