Synthesis of thick and high-quality homoepitaxial diamond with high boron doping level: Oxygen effect

Abstract

Heavily boron doped CVD diamond growth in oxygen-containing carbon/hydrogen gas mixtures was investigated. The dependence of boron incorporation efficiency on the oxygen content in the gas phase was studied, as well as the electrical characteristics of the grown layers. The changes in the microwave plasma discharge with the increase of boron (500 to 40,000ppm) at different oxygen contents (O/C=0.02, 0.1 and 0.5) was investigated by OES. The behavior of the BH emission line indicate an existence of a “reservoir” for boron due to the presence of oxygen, which limits the production of BH radicals up to B/C=10.000ppm. It is shown that thick (>100μm) heavily-doped diamond layers (boron concentration>1020cm−3) can be obtained in the oxygen-containing carbon/hydrogen gas mixtures at high power density growth conditions (MWPD=130W/cm3), allowing high quality deposition at a reasonably high growth rate 4μm/h.