Supersonic molecular beam growth of epitaxial beta-SiC on Si(100).

摘要

his dissertation examines the control of reagent kinetic energy as a growth parameter during the molecular beam deposition of epitaxial ;With the precursor hexamethyldisilane, pronounced enhancement of film growth efficiency (up to 20 times) is obtained in the incident energy range 0.1-2.8 eV due to the collisional activation of the dissociative chemisorption step. However, incident energy exhibits negligible effect on the crystallinity and morphology of the films when compared to the more apparent effect of growth temperature (800-1100 K). A growth mechanism involving outdiffused silicon atoms is identified and consistent with the effects of growth temperature and incident flux as well as the independence of film morphology on incident energy. Because growth ceases at temperatures below 1100K in the absence of silicon atoms even at 2.8 eV incident energy, it is impossible to achieve a lower onset growth temperature for ;With the precursor methylsilane, incident energy displays dramatic effects on film morphology in addition to the enhancement of film growth efficiency. An alternative growth mechanism is opened up at moderately high incident energies (0.45 eV) possibly due to the presence of methylsilyl radicals in more abundant surface concentrations as a result of the collisional activation of the dissociative chemisorption. This allows continuous growth of films of improved quality compared to films obtained from hexamethyldisilane. A key result of this work is the further lowering of the onset growth temperature for epitaxial