H. Akazawa et al., SYNCHROTRON-RADIATION STIMULATED EVAPORATION AND DEFECT FORMATION IN A-SIO2, Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms, 91(1-4), 1994, pp. 644-647
The relation between synchrotron radiation stimulated evaporation and
oxygen vacancy defect formation in a-SiO2 was investigated. The behavi
or is shown to be quite different for the following three temperature
regimes. At temperatures lower than 500-degrees-C, the surface is soon
covered by a thin SiO(x) (x < 2) layer upon SR irradiation. The film
is etched by stimulated ejection of surface atoms from the SiO(x) laye
r. Between 500-700-degrees-C, film removal is rate-limited by the ther
mal desorption of SiO molecules. Accordingly, a thick layer of SiO(x)
is accumulated over the surface. Above 700-degrees-C, the evaporation
of a-SiO2 proceeds at a constant rate keeping the surface stoichiometr
y Of SiO2. This indicates that an SiO(x) layer, even if created, is th
ermally decomposed.