Is sulfur a donor in diamond?

Homoepitaxial diamond layers grown by chemical-vapor deposition in the pres ence of H2S, which were published to exhibit n-type conductivity, are caref ully analyzed both electrically and structurally. Hall-effect measurements as a function of temperature clearly show the samples to exhibit p-type con duction, with an activation energy, carrier concentrations, and mobilities which very much resemble those of B-doped p-type diamond. Secondary-ion-mas s spectroscopy confirms that indeed the samples, previously claimed to be n type due to a donor state attributed to sulfur, contain enough unintention al boron to explain the observed p-type features. (C) 2000 American Institu te of Physics. [S0003-6951(00)04606-4].