Nucleation of diamond on silicon by biased HFCVD: A comparative study

Abstract

The first stages of diamond deposition on pristine silicon by the bias assisted hot filament CVD technique were studied. Two different experimental setups were used to clarify the role played by negative bias in the nucleation process. In the first setup, a negative bias was applied 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 1010 cm−2, which was six orders of magnitude higher than that obtained when no bias was used to assist the process. AES and Raman analyses revealed that the material formed under such biasing conditions was basically a mixture of diamond and sp2 carbon. In the second setup, a negatively biased diamond coated tungsten electrode was placed between the filament and the substrate. In this case, diamond formation was detected by AES and Raman measurements even for very short bias times. Bias voltages higher than 300 V markedly enhanced diamond nucleation 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.