Effects of oxygen and pressure on diamond synthesis in a magnetoactive microwave discharge

The effects of oxygen addition and total pressure on the synthesis of diamond have been studied in a magnetically enhanced microwave discharge. Diamond films were deposited on silicon substrates at substrate temperatures from 540 to 650 °C and total pressures from 2 to 20 Torr, and were characterized by microprobe and macrochamber Raman spectroscopy and scanning electron microscopy. Without oxygen, Raman spectra of these films display only graphitic peaks. As oxygen is added, faceted crystalline diamond is observed in scanning electron microscope micrographs and a sharp diamond peak in the Raman spectrum appears. With 2% oxygen, diamond films exhibiting a pure diamond Raman peak at ∼1334 cm−1 with very small nondiamond carbon peaks were grown at relatively low temperature (∼600 °C) and low pressure (5–10 Torr).