The plasma hydrogenation of laser-crystallized and amorphized films was investigated. The H concentration was found to be equal to 1.5at% by applying a laser-induced H effusion method to 20nm-thick crystallized films which had been hydrogenated at 250C for 30s. The defect density was reduced from 1017 to 4 x 1016/cm3. The H concentration was equal to 2.5at% in amorphized films which were 12nm thick. This low H concentration resulted in a low optical band-gap energy of 1.7eV for amorphized films, while the width of the Urbach tail was 0.06eV. This value was close to that for hydrogenated amorphous Si films which were prepared by using radio-frequency glow discharge techniques. The defect density of laser-amorphized Si films was reduced from 2 x 1020 to 4 x 1015/cm3eV, as compared with amorphous hydrogenated Si films which were fabricated by means of radio-frequency glow discharge.

T.Sameshima, M.Sekiya, M.Hara, N.Sano, A.Kohno: Journal of Applied Physics, 1994, 76[11], 7377-83