A novel high-density and low-temperature microwave discharge utilizing a spoke antenna has been applied for the fast deposition of microcrystalline silicon (muc-Si:H) films with preferred (2 2 0) orientation. Systematic deposition studies were performed from pure and H-2-diluted SiH4 systems with microwave power, total pressure, H-2 dilution ratio and substrate temperature as variables, combined with plasma diagnostics using optical emission spectroscopy and Langmuir probe techniques. The effects of deposition parameters on the film crystallinity, crystal orientation and defect density are demonstrated. (C) 2002 Elsevier Science B.V. All rights reserved.