Hydrogenated amorphous silicon films were deposited in a modified square wave modulated pulsed plasma discharge at 13.56 MHz using silane diluted with hydrogen, helium, and their mixtures at two different modulation frequencies. The deposition rate is found to be higher in helium diluted plasmas and also at 10 Hz modulation. Increasing the modulation frequency from 2 to 10 Hz increases the deposition rate at all dilutions with helium or helium and hydrogen. At 2 Hz modulation, the deposition rate in helium diluted silane is higher and tends to saturate with increasing dilution whereas with hydrogen dilution it decreases. In helium diluted discharge with 10 Hz modulation the material properties deteriorate. However, the addition of hydrogen to helium diluted silane improves the film properties. The decrease in the deposition rate in hydrogen, and hydrogen and helium diluted plasmas is attributed to atomic hydrogen mediated etching of the growth surface which also explains the improvements in optoelectronic properties of these films. Hydrogen content, hydrogen bonding configurations, and the defect density also depend on the dilution ratio and modulation frequency.