Properties of magnetron sputtered hydrogenated amorphous silicon

Hydrogen concentrations and bonding configurations were studied in hydrogenated amorphous silicon (a-Si:H) films deposited at 50‡C using the magnetron mode of sputtering with partial hydrogen concentrations between 0 and 90 percent in flowing argon. Hydrogen content within the films was determined from nuclear reaction analysis, and the chemical bonding of hydrogen was determined from infrared absorption of as-deposited, thermally annealed, and ion-bombarded films. Hydrogen/silicon ratios in the films increase to a maximum of 0.31 with increasing hydrogen in the deposition system. Ion backscattering shows ∼ 6 at.% argon trapped in the films, but no oxygen was detected by either ion backscattering or by sputter-Auger analysis. The wag and bend modes for Si-H in the films are typical of sputter-deposited a-Si:H; however, the stretch mode region is atypical with absorption near 2000 cm^−l dominating even for H/Si ratio of 0.27. From results of thermal annealing and post-deposition ion bombardment, it is concluded that argon ion bombardment during deposition produces enhanced absorption near 2000 cm^-1 in these a-Si:H films deposited by magnetron sputtering. This work was sponsored in part by the U. S. Department of Energy, under Contract DE-AC04-76-DP00789 and the U. S. Army Research Office, Contract DAA29-79-C-0026. U. S. Department of Energy facility.