Hydrogenated Amorphous Silicon: Hydrogen Content, Bonding Configurations and Morphology in Sputter-Deposited , In-Chamber Annealed Thin Films

The infrared absorption features of sputter-deposited amorphous silicon (a-Si:H) thin films prepared under different substrate temperatures (T(s)) and an in-chamber annealing treatment were analysed as a function of annealing temperatures ranging from 200 to 600-degrees-C. Fourier-transform infrared absorption spectroscopy and scanning electron microscopy were used to analyse the evolution of film characteristics after annealing. Hydrogen bonding configurations for higher T(s), in-chamber annealed samples showed a higher proportion of monohydride grouping, and further annealing steps revealed that hydrogen is much more tightly bonded under these deposition conditions than when T(s) is lower and the in-chamber annealing treatment not used. Oxygen and nitrogen contamination, both during and after deposition, have also been found to be reduced when samples were in-chamber annealed. Samples deposited at low T(s) and not in-chamber annealed showed the same surface damage as samples prepared at higher T(s) and which were then annealed at temperatures starting at 300-degrees-C, indicating a high degree of stress, probably caused by an excessive hydrogen concentration in films prepared at lower T(s).