Enhanced nucleation of diamond films assisted by positive dc bias

Diamond nucleation on untreated silicon was enhanced by positive dc biasing in a horizontal microwave plasma chemical vapor deposition system. The effects of process parameters of bias voltage, methane content, bias time, working pressure and microwave power on the diamond nucleation were investigated. A nucleation density higher than 1010 cm−2 was achieved on an untreated, mirror-polished silicon substrate by positive dc biasing. With a bias voltage between the range of +200 and +300 V, it was found that high methane content is effective in the enhancement of diamond nucleation. It was also found that amorphous carbon was formed under the positive dc bias conditions. Uniform diamond films were obtained by combining the positive dc bias enhanced nucleation process with subsequent growth under the usual microwave plasma chemical vapor deposition diamond conditions. Diamond films deposited were characterized by scanning electron microscopy and Raman spectroscopy. The effect of positive dc biasing on nucleation at a high methane content to generate oriented diamond nuclei on (100) Si substrate was explored.