Low-temperature diamond growth in a pulsed microwave plasma

Abstract

Polycrystalline diamond films have been synthesized at backside substrate temperatures down to 300 °C in a low-pressure CH4–H2–O2 microwave plasma. Diamond growth at low substrate temperatures was greatly assisted by magnetic field discharge activation and by pulse modulation of the input microwave power. Diamond films grown at backside substrate temperatures of 300–500 °C exhibit characteristic 1333 cm−1 Raman phonon peaks with linewidths of 5.7–3.1 cm−1, while scanning electron micrographs show clearly defined crystallites. The nondiamond carbon content of the films remains low for temperatures down to 350 °C, as estimated from the broad peak of the Raman spectra around 1550 cm−1.