EFFECT OF NATIVE SIO2 LAYER ON THE NUCLEATION OF DIAMOND USING A COMBUSTION-FLAME

The effect of native oxide thickness on the nucleation of diamond was investigated. The initial thickness of the native oxide on Si substrat es was varied using three surface treatment methods: ultrasonic scratc hing, HF acid etching, and a combination of the two. The oxide layer w as also modified during the experiment by using a low O-2:C2H2 ratio p regrowth treatment (R(f)=0.93, d=15 mm). The use of HF acid eliminated the oxide layer within the detectable limits of the X-ray photoelectr on spectroscopy analysis (about 3 Angstrom). A low gas ratio pregrowth treatment process (oxygen-to-acetylene ratio R(f), set to 0.93) meant that diamond crystals were formed after 30 s and a complete him in th e center of the deposition area after 180 s. The low gas ratio pregrow th treatment suppressed the formation of the oxide layer relative to s tandard growth conditions (R(f)=0.97, d=10 mm). However, it was determ ined that despite this low gas ratio treatment SiO2 formation was poss ible inside the acetylene feather.