Structural, Optical and Electrical Characterization of Amorphous Carbon Thin Films Grown on PTFE Substrates for Photovoltaic Application

The n-type conductivity of nitrogen doped amorphous carbon films have been grown on p-type silicon, quartz and heat tolerant (up to 260 degC) flexible polytetrafluoroethene plastic substrates by microwave (MW) surface wave plasma (SWP) chemical vapor deposition (CVD) at low temperature (<100 degC). For film deposition at gas composition pressure of 50 Pa in the CVD chamber, we used argon as carrier gas, nitrogen as dopant and methane as carbon plasma source. Photovoltaic effects of the films as well as their chemical composition, bonding and structural properties have been studied. The X-rays photoelectron spectroscopy measurement shows that nitrogen content in the films grown on plastic substrates is higher compared with the films grown on quartz substrates. The optical measurements show that the optical band gap of the films grown on plastic substrate is lower compared with the films grown on quartz at the same parameters. The temperature dependence conductivity and photoresponse measurements show that the electrical conductivity of the films grown on plastic substrates is much higher compared with the films grown on quartz substrates