ELECTRICAL CHARACTERISTICS OF PLASMA-DEPOSITED DIAMOND-LIKE CARBON SILICON METAL-INSULATOR SEMICONDUCTOR STRUCTURES

Diamondlike carbon (DLC) films were deposited on n-type silicon substrates by the plasma decomposition of butadiene and two binary mixtures of butadiene with hydrogen or argon. The ac conductance and capacitance characteristics for the DLC/silicon metal-insulator-semiconductor (MIS) structures were measured over a range of frequencies. The electrical characteristics of the DLC film deposited from a pure butadiene plasma were strongly influenced by carrier tunneling into the traps located in the film. The films exhibited large flatband voltage and hysterisis. However, in the films deposited with both hydrogen and argon, the traps on the insulator side were reduced and the effects due to film charges and hysteretic instability could be eliminated. The addition of argon, however, increased the density of interface states. The presence of hydrogen in the deposition gas mixture improved the interfacial characteristics significantly. The density of interface states for DLC/Si MIS with the insulating DLC layer deposited from a butadiene/hydrogen plasma was estimated to be 4 X 10(10) eV-1 cm-2.