Studies of the Oscillator Strengths of Infrared Vibrational Modes in Glow‐Discharge Hydrogenated Amorphous Silicon

The infrared oscillator strengths of the stretching and wagging/rocking modes in glow‐discharge hydrogenated amorphous silicon, a‐Si, is compared to similar data reported recently for sputtered material. For both materials the integrated band intensity of the wagging/rocking mode at 640 cm⁻¹ is proportional to the total hydrogen concentration, N_H and is independent of preparation conditions. The derived oscillator strength for the latter mode is identical in glow‐discharge and sputtered a‐Si films. In contrast, the integrated band intensity of the composite silicon‐hydrogen stretching mode is film dependent; the derived average oscillator strength, Γ_s (2000 + 2100), is significantly smaller in glow‐discharge, compared to sputtered a‐Si. A reanalysis of previous isothermal dehydrogenation data is presented in which Γ_s (2000 + 2100) is shown to be a function of N_H and increases markedly at hydrogen contents < 10 at%. No conclusions can be drawn, however, concerning the oscillator strengths of the deconvoluted bands at 2000 and 2100 cm⁻¹ occurring within the stretching region. A previously proposed model for the mechanism of the dehydrogenation of a‐Si is unaffected by the present results.