Thermal decomposition of an ultrathin Si oxide layer around a Si(001)-(2 x 1) window.

We examine the thermal decomposition of an ultrathin Si oxide layer around a Si(001)-(2 x 1) window opened by electron-beam-induced selective thermal decomposition. The decomposition progresses at the oxide/Si(001)-(2 x 1) boundary and follows two rate-limiting steps with activation energies of 4.0 and 1.7 eV. We propose that the former and latter energies correspond to the reaction of Si monomer with the oxide and the desorption of the SiO into the vacuum, respectively.