Investigation of homoepitaxial growth by microwave plasma CVD providing high growth rate and high quality of diamond simultaneously

Abstract

Single crystal diamond (SCD) growth on (100)-oriented high-pressure high-temperature (HPHT) type 2a diamond substrate was investigated to optimize growth conditions providing high growth rate and high quality of diamond simultaneously. CVD operating regime for SCD synthesis was determined which allows achieving the highest possible growth rate and at the same time the minimum number of defects in diamond at minimum amount of nitrogen (less than 200 pbb) in the reactor. At the optimized microwave plasma CVD growth condition at high power density the formation of non-epitaxial diamond crystallites or hillocks or polycrystalline diamond rim around the SCD top surface was prevented. The high power density was achieved with a relatively low gas pressure of 160 Torr due to local electric field amplification above the substrate holder with projection. High quality SCD grown with a relatively high growth rate in the range of 6−8 μm/h at a microwave power of 3 kW and a temperature of 900 °C was obtained. It was found that the formation of surface defects could be effectively suppressed by choosing the misorientation angle of the substrate surface. At this angle the step-flow growth regime was implemented. By choosing the misorientation angle, CH4/H2 ratio and the power density or the concentration of atomic hydrogen the high quality SCDs of 1 mm thickness were successfully grown.