EFFECTS OF HYDROGEN ON ELECTRICAL PROPERTIES OF N-TYPE PHOSPHOROUS-DOPED DIAMOND EPITAXIAL FILM

摘要

An phosphorous (P) doped diamond epitaxial film grown by GSMBE using methane and tri-n-butylphosphine showed an n-type conduction and a fall of the electrical conductivity (σ) after the surface oxidation. From C1s XPS measurements the component of 284.2 eV which has been assigned to hydrogenated carbon in the near surface region decreased. Comparing the electrical measurements with the XPS observation, we found that the hydrogenated carbon contributes not to the n-type conduction but to the high σ. The variable activation energy of σ of 0.24 and 0.12 eV which were low relative to an isolated P donor level of 0.43 eV in diamond are explained qualitatively by a theoretical prediction about a codoping of P donors and H acceptors. The electron mobility at 450℃ was obtained to be 1010 cm~2/Vs when the σ and the Hall coefficient were analyzed by considering the existence of P donors and H acceptors.