Fabrication and characterisation of a new sensing device based on hydrocarbon groups (CHx) coated porous silicon

In this work, we have fabricated a gas-sensing device based on hydrocarbon groups (CHx)/porous silicon (PS) structure. The porous layer was prepared electrochemically from p-type silicon. The porous samples were coated with hydrocarbons groups (CHx) deposited by plasma of methane under argon atmosphere. nd that heterojunction fabricated from thin CHx layer shows a good rectifying behaviour. This property, correlated with the porous silicon sensitivity to the gas environments, can be effectively used to realise heterojunction diodes whose current–voltage (I–V) characteristics are modified by the gas reactivity on the porous surface. ivity of those devices, response time and impedance response to different gas exposure (ethylene, ethane and propane) have been investigated. spectroscopy measurements in different gas environments show a reversible free-carrier detrapping in the IR region.