Microcrystalline silicon (μc-Si:H) solar cells were prepared in a wide range of deposition parameters using 13.56 MHz plasma-enhanced chemical vapour deposition (PECVD). The best μc-Si:H solar cells were prepared close to the transition to amorphous silicon (a-Si:H) growth at very high deposition pressures (∼ 10 Torr) showing solar cell efficiencies up to 8.0% at a deposition rate of 5 Å/s. Investigations of the solar cells were performed by Raman spectroscopy and transmission electron microscopy (TEM). TEM measurements revealed similar structural properties with similar high crystalline volume fractions for these cells although they showed distinctly different efficiencies. However, an increased amorphous volume fraction was detected by Raman spectroscopy for the low efficiency cells prepared at low deposition pressures. This result is attributed to an increased ion bombardment at low pressures.