The spin-lattice relaxation time of high-quality hydrogenated amorphous material was measured by using a saturation method. The relaxation time for neutral Si dangling bonds at 77K was found to increase rapidly with increasing light-soaking time, and then tended to saturate. This behavior was similar to that of the Urbach energy, which reflected the randomness of the amorphous network structure. The spin-lattice relaxation times for 3 components of the light-induced electron spin resonance were also measured at 77K. It was found that the relaxation times for both broad and narrow components decreased with light soaking. The results showed that the change in spin-lattice relaxation time of dangling bonds was not directly related to their density, but was closely related to the overall network structure.

Change in spin-lattice relaxation time with light soaking for defects in hydrogenated amorphous silicon T.Shimizu, K.Kata, M.Mitani, M.Kumeda: Japanese Journal of Applied Physics - 1, 1998, 37[10], 5470-3