The role of secondary gas-phase reactions during plasma-enhanced chemical vapor deposition of microcrystalline silicon is a controversial subject. In this paper, we show that the enhancement of such reactions is associated with the improvement of material properties of absorber layers deposited at high constant rate. We detect powder, a product of secondary gas-phase reactions, via infrared laser absorption spectroscopy, laser light scattering, and optical emission spectroscopy. As the powder formation is increased, we measure a systematic improvement of device performance. This demonstrates that secondary gas-phase reactions are not detrimental to the material quality of microcrystalline silicon deposited at high rate. © 2010 American Institute of Physics.