Diamond-Like Films As A Protecting Insulator For Gas-Detecting Suspended-Gate Field-Effect Transistors

Diamond-like (hydrogenated amorphous carbon (a-C:H)) films have been investigated as protective gate insulator for gas-sensitive suspended-gate field effect transistors (SGFETs). The electrical film properties such as bulk and surface resistivity, dielectric constant, dielectric strength as well as interface state density to silicon have been characterized. The chemical stability with respect to gaseous species was measured with a Kelvin probe. The process sequence for the incorporation of a-C:H films into the SGFET is discussed. Gas measurements with SGFETs show that, in comparison with common insulators, a-C:H greatly improves device stability and reliability.