Ion-Assisted Nucleation of Diamond
STANFORD UNIV CA DEPT OF MATERIALS SCIENCE AND ENGINEERING
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Diamond thin films are envisioned for a wide variety of applications due to the unique chemical, mechanical, electrical, and optical properties of this material. However, deposition limitations currently prevent the realization of many of these applications. The nucleation of diamond is one critical limitation which severely restricts the use of diamond films for emerging technologies. The nucleation process dictates the structure and morphology of the diamond thin films therefore, nucleation ultimately affects a wide range of film properties including adhesion, strength, thermal and electrical conductivity, and optical transmissivity. Without specific pretreatments to overcome nucleation problems, heterogeneous diamond nucleation is inadequate for use in most applications. Therefore, several techniques for improving diamond nucleation were investigated in this thesis to improve the understanding of this critical aspect of diamond technology. Thin carbon films with varied structure proved ineffective for nucleation enhancement. Scratchingabrasion of substrates with diamond powder significantly enhanced nucleation, however, associated with this technique are a number of disadvantages. Ion assisted nucleation, also called bias enhanced nucleation, is a promising in situ technique for diamond nucleation densities in excess of 10exp 10 cm-2. In this process a negative bias is applied to the substrate in a microwave plasma chemical vapor deposition MPCVD system. The bombardment of the substrate by energetic carbon ions during the bias pretreatment controls the nucleation. A critical bias voltage is required for significant nucleation enhancement and the process is relatively independent of temperature and carbon concentration over specific ranges.
- Atomic and Molecular Physics and Spectroscopy
- Nuclear Physics and Elementary Particle Physics