The role of ion bombardment process in the formation of insulating and semiconducting plasma deposited carbon-based films

Abstract

In recent years, an audio-frequency (10–50 kHz) glow discharge has been successfully used for plasma deposition of various types of thin films (such as a-SiXCY:H, a-GeXCY:H, a-SnXCY:H and a-PbXCY:H) from organic compounds of the carbon family. It has been found that two forms of the films with drastically different electronic properties, namely amorphous insulators (a-I) and amorphous semiconductors (a-S), can be fabricated. Transformation in the structure from a-I to a-S forms (called the a-I–a-S transition) is caused by only small changes in the impact energy of ions bombarding the growing film. In the paper, the role of the bombardment process in the a-I–a-S transition is thoroughly discussed. Rough calculations show that the cleavage of C–X bonds (X=Si, Ge, Sn, Pb) on the surface of deposited film by impinging ions is a crucial stage of the a-I–a-S transition.