CHARACTERIZATION OF HETEROJUNCTION DEVICES CONSTRUCTED BY AMORPHOUS DIAMOND-LIKE FILMS ON SILICON

The electronic properties of amorphous diamondlike carbon (DLC) films on silicon were examined for their capability for application to elect ronic devices. Metal-insulator-semiconductor (MIS) diodes and p-n hete rojunction devices were created and characterized, The films used were grown using rf plasma assisted CVD of methane. They were grown ou n-t ype silicon (100) wafers, Their structural composition was identified by Raman spectroscopy, ellipsometry, and x rays. They showed an insula ting behavior and they were suitable for the creation of MIS devices. They showed extremely low internal conductivity due to defect currents , This conductivity showed a behavior of the form I similar to T-1/4. Then the density of trapping stares at the silicon/carbon interface wa s measured using the conductance technique. The aim of investigating t he nature and behavior of these states was to determine the magnitude of the density of states and try to find a way to reduce it. Thus opti mization of the DLC/silicon interface could be made, for future refere nce to the construction of heterojunction devices containing tile DLC/ silicon configuration. The values of the density of stales were of the order of 10(11)-10(12) cm(-2) eV(-1). Annealing had the effect of red ucing the magnitude of the D-it. The ion implantation technique was us ed to transform the insulating DLC films into semiconducting by adding boron ions as dopants to achieve p-type conductivity. Thus p-n hetero junction devices were made, having silicon as one of the elements and DLC as the other element, Four different doses of boron were implanted , producing different conducting properties of the DLC films. Those de vices performed like Schottky diodes for low boron doses and like p-n diodes for high doses. (C) 1997 American Institute of Physics.