NUCLEATION OF DIAMOND ON SILICON BY BIASED HFCVD - A COMPARATIVE-STUDY

The first stages of diamond deposition on pristine silicon by the bias assisted hot filament CVD technique were studied. Two different exper imental setups were used to clarify the role played by negative bias i n the nucleation process. In the first setup, a negative bias was appl ied directly to the substrate. For negative biases in the 300 V range, a great increase of the nucleation density was found, with values up to 10(10) cm(-2), which was six orders of magnitude higher than that o btained when no bias was used to assist the proc:ess. AES and Raman an alyses revealed that the material formed under such biasing conditions was basically a mixture of diamond and sp(2) carbon. In the second se tup, a negatively biased diamond coated tungsten electrode was placed between the filament;Ind the substrate. In this case, diamond formatio n was detected by AES and Raman measurements even for very short bias times. Bias voltages higher than 300 V markedly enhanced diamond nucle ation density, although this enhancement was not as notable as in the first setup. In both cases, XPS and AES studies detected the presence of SiC as a result of bias treatment. (C) 1998 Elsevier Science S.A.