a-Si:H intrinsic films and their solar cells were prepared by DC-PECVD with growth rates of 1, 3, and 10 Å/s. Raman, IR, and PL spectroscopies were used to study the i-layer properties in relation to the solar cell performance. Raman shows an identical TO mode for all the samples, which indicates the local silicon-bonding configuration does not change with the growth rate from 1 to 10 Å/s. IR results show that the hydrogen bonding configuration is monohydride (Si-H) dominated, and the hydrogen content obtained from the 630 cm-1 wagging mode is 12-14 at.%. Surprisingly, a very small absorption strength for the stretching 2000-2100 cm-1 mode was found for some samples deposited at the higher growth rates (3, 10 Å/s). For these same samples, the PL spectra exhibit a red shift. Both the IR and PL results might be related to the same microstructures formed at high growth rates. We found that although the properties of the i-layer varied as the growth rate increased from 1 to 10 Å/s, the performances of the cells were comparable (within about 4%).