EFFECT OF SURFACE-DEFECTS ON CVD DIAMOND NUCLEATION ON 6H SIC

The thin SiC layer often observed between a Si substrate and a diamond him has led to the belief that the formation of this SiC layer preced es diamond nucleation. However, the nucleation of diamond on a clean, undamaged SiC surface is difficult. Some of the defects introduced by abrading the surface of many substrate materials with diamond powder b efore deposition appear to serve as nucleation sites. Atomic-scale def ects (vacancies, interstitials) and impurities can be introduced by io n implantation. Single-crystal 6H SIC with the external face composed of Si or C were implanted with silicon (150 keV) and carbon (55 keV) i ons at fluences between 2 x 10(14) ions cm(-2) and 2 x 10(15) ions cm( -2). Nucleation did not occur on as-received or implanted samples. Abr asion with diamond powder using an ultrasonic cleaner bath caused prof use nucleation on all samples. It was found that nucleation density on abraded samples decreased when implanted with increasing fluence of i ons. Fluences of 2 x 10(14) Si+ ions cm(-2) (150 keV) and 4 x 10(14) C + ions cm(-2) (55 keV) did not effect the nucleation of diamond on sil icon carbide. However, a fluence of 2 x 10(15) Si+ ions cm(-2) complet ely suppresses the nucleation of diamond. Rutherford backscattering sp ectrometry/channeling studies on the high-fluence-implanted silicon ca rbide sample showed the presence of an amorphous surface layer suggest ing that CVD diamond does not nucleate on amorphous SiC.