Asian Program

Japanese

Data

Former Fellows

Dissertation Abstracts

Korea

Name	Sung-Hoon KIM
Position	Associate Professor Department of Nano Materials Chemistry & Engineering, Silla University
Japanese Advisor	Hideo ITOZAKI Professor,Osaka University

  For the enhancement of the diamond film properties, a new method, what is called the cyclic process, is invented. It can be simply achieved by turning a source gas flow rate in a reaction system on or off. Irrespective of the substrate kinds and deposition conditions, the diamond nucleation density was enhanced by the cyclic process. Therefore the selective deposition of diamond film on glass substrate could be achieved using the cyclic process. The highest nucleation density was obtained under the condition of the higher growing/etching time ratio in the cyclic process. Conversely, the diamond quality was enhanced under the condition of the lower growing/etching time ratio in the cyclic process. For the cyclic modulation time interval, namely the time for on cycle in the cyclic modulation process, both the diamond nucleation density and the diamond quality were enhanced with increasing the cyclic modulation time interval. For the effect of the cyclic process to the texture growth of diamond film, first of all, the increase in the density of {100}-oriented grains as well as the film uniformity is investigated. The film uniformity increased by applying the cyclic process during the nucleation step. The carburization and bias-enhanced nucleation conditions are examined as a function of the reaction time. The evolution of the film morphology indicates that the increase in the carburization time decrease the tilted angle of the {100}-oriented texture morphology. The ball-like agglomerates formed by carburization probably act as nucleation sites for diamond. The density of agglomerates is independent of the carburization time, but their size increases with increasing carburization times. The application of the cyclic process during the nucleation step can lead to a decrease in the density of larger agglomerates. The cyclic process applied during the growth step has a detrimental effect on the {100}-oriented texture growth. In contrast, the coverage area of the film as well as the density of {100}-oriented diamond grains could be increased by applying the cyclic process. The properties of the diamond film were found to be strongly dependent on the etching time interval in the cyclic process. With less etching time than growing time in the cyclic process, not only the density of the {100}-oriented textural grains, but also the parallel degree of the {100} plane of the film with respect to the substrate, were proved to be enhanced. During the cyclic process, the current on the substrate, which was induced by the plasma, and the gas components in the plasma were measured. Based on these results, the causes for the cyclic process effect on the diamond film properties were discussed in detail. In addition, the growth distributions of the diamond grains on the substrate surface according to the different process are described step by step.