Homoepitaxial diamond growth with sulfur-doping by microwave plasma-assisted chemical vapor deposition

Abstract

We have investigated sulfur incorporation and the effects of H 2S addition on the crystal quality and electrical properties of sulfur-doped homoepitaxial (100) and (111) diamond grown by microwave plasma-assisted chemical vapor deposition. In the case of (100) homoepitaxial growth, adding a small amount of H 2S effectively improved the crystal quality, whereas adding an excess of H 2S degraded the crystal quality. The amount of incorporated sulfur increased with increasing amounts of H 2S. At the same time, the amount of undesirable silicon impurities decreased. Adding H 2S in the range of 50–100 ppm yielded a high-quality S-doped diamond. In a temperature range of 250–550 K, the high-quality S-doped homoepitaxial (100) diamond showed n-type conduction by Hall-effect measurements. The electrical properties of S-doped (100) diamond were sensitive to the quality of the crystal. The crystal quality of the S-doped (111) homoepitaxial diamond was poorer than that of the (100) diamond. The quality of the S-doped (111) diamond was insensitive to the amount of additional H 2S. The resistivity of the (111) diamond was very high compared to that of the (100) diamond. The resistivity of the undoped (111) diamond was lower than that of the S-doped (111) diamond. The Hall effect measurement could not be performed on the (111) homoepitaxial diamonds.