A low power density very-high-frequency (VHF) (55 MHz) H2 plasma in a capacitively coupled multihole-cathode (MHC) geometry is studied using Langmuir probe measurements. Radial profiles show a higher ion density (N i) and lower electron temperature (Te) compared to a MHC 13.56 MHz H2 plasma. The Ni dependence on power indicates an Ohmic plasma, while Te is essentially constant. The MHC-VHF plasma is used to investigate mixed phase microcrystalline+amorphous (μc+a-) Si:H thin films at a substrate temperature of 60 °C. High-resolution photoemission suggests two types of Si, with concentrations in agreement with atomic force microscopy images showing ∼510±40 nm crystallites embedded in a-Si:H matrix. The results show that the low power density MHC-VHF plasma is a high-Ni Ohmic collisional plasma, suitable for low temperature deposition of μc + a-Si:H thin films.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)