The 29Si hyperfine structures of light-induced electron spin resonance centres with g = 2.004 and 2.01 were investigated in undoped hydrogenated amorphous samples with 29Si contents of 1.6, 4.7 or 9.1at%. Overlapping light-induced electron spin resonance signals were deconvoluted by using differences in spin-lattice relaxation times between the 2 signals. The deconvoluled 29Si hyperfine structure of g = 2.004 indicated that the wave function of this centre spread mainly over two Si atoms. It was therefore proposed that the cause of g = 2.004 was electrons trapped in antibonding states of weak Si-Si bonds, rather than those trapped at positively charged dangling bonds. The isotropic hyperfine splittings were estimated to be about 7mT for g = 2.004 and below 3mT for g = 2.01. These data were in good agreement with the characteristics of the antibonding and bonding states of the weak Si-Si bond.

Microscopic Origin of Light-Induced ESR Centres in Undoped Hydrogenated Amorphous Silicon. T.Umeda, S.Yamasaki, J.Isoya, K.Tanaka: Physical Review B, 2000, 62[23], 15702-10