Optically induced metastable defects in undoped a-Si:H

Publisher Website
Google Scholar
Abstract
A pulsed electron spin resonance (ESR) technique has been applied to undoped hydrogenated amorphous silicon (a-Si: H) to obtain a detailed spectrum of optically itiduced ESR over a wide dynamie range, and to measure the spin-lattice relaxation curve directly in the time domain. It has been found that the optically induced ESR spectrum involves a 29Si hyperfine structure which is like that of the dangling-bond state in the dark, and that the spin-lattice relaxation curve in the dark and under optical excitation are quite similar. It has also been found that the optically induced ESR signal accompanies an inerease in the sub-bandgap optical absorption. These observations suggest that the optically induced ESR originates from the localized states similar to singly oceupied dangling-bond states. The phenomenological similarity of the optically induced ESR in undoped a-Si: H with that in chalcogenide glasses as well as in amorphous arsenie is pointed out and discussed in terms of the network connectivity.