Electric Properties Of Diamond-Like Carbon Film Grown By PECVD

Diamond-like carbon films (DLC films) is an amorphous carbon material. As having many similar natures with the diamond, diamond-like carbon technology has been applied in many fields. The doped DLC film is a kind of semiconductor materials. The band gap of DLC film is adjustable between 1 to 4eV. It could be used in optoelectronic devices fields, such as solar cells and photoelectric detectors. In the existing studies about the electrical properties of DLC films, metals, such as Al and Au, were chosen to contact with DLC films, with a assumption that the contacts were ohmic. But nobody confirmed the contacts between DLC films and Au or Al were ohmic, nor explored the nature of contacts between DLC films and other metals.In this paper, DLC film is grown by radio frequency plasma enhanced chemical vapor deposition (RP-PECVD). Selecting CH₄ as the source of gas, NH₃ or BH₃ as a source of doping, the levy and a variety of doped DLC films were grown on the silicon and quartz. The regular growth, structure, photoelectric and other characteristics were studied by using many structure and photoelectric detection means, such as ellipsometry, Auger spectroscopy, Raman spectroscopy, atomic force microscope, high precision ammeter and so on. This study was interested in the electric properties about the contacts between different types of doped DLC films and metals, such as Al, Ti, Ni, Au and Zr. Metals were planted on the levy and doped DLC films as the electrodes, which formed a structure of MSM. Then by detecting the I-V curves, the types of the contacts between metals and DLC films were judged. And also a simplified model of the measurement circuit was established to calculate the resistivity of DLC films. It was proved by experiments that the contact between the metals and DLC films is ohmic. This phenomenon can be explained that the electric conducted transited between the impurity energy level. Based on the study of the growth of diamond-like carbon films, characterization and electrical properties, this article try to explain the DLC film conductive mechanism and provided the foundation to improve the growth process and achieve effective doping in the future.