Isothermal and isochronal electron spin resonance studies were made of the recovery of paramagnetic Si3=Si• Pb centres, at the (111)Si/SiO2 interface, during vacuum-annealing. Previous work had indicated a simple exponential decay of hydrogenated Pb, [PbH], as a function of time. This was taken to be evidence that the process obeyed a first-order rate equation, although the data was inadequate to prove this. Improved experimental techniques revealed a clearly non-simple exponential decay, and even a simple thermal model revealed the existence of a distinct spread of activation energies. The incorporation of a Gaussian spread led to a consistent generalized simple thermal model that reflected the physical insights. The deduced attempt frequency was close to the Si-H wagging-mode frequency, and this offered a clue as to the atomic dissociation mechanism. The spread in activation energies resulted from interfacial stress-induced variations in the Pb-defect morphology. The data were incompatible with second-order kinetics; thus indicating that PbH dissociation was an individual process.

Dissociation Kinetics of Hydrogen-Passivated Pb Defects at the (111)Si/SiO2 Interface A.Stesmans: Physical Review B, 2000, 61[12], 8393-403