Growth and characterization of phosphorous doped {111} homoepitaxial diamond thin films

An $n$ -type semiconducting diamond thin film was obtained by microwave enhanced plasma chemical vapor deposition using phosphine $({\mathrm{PH}}_{\mathrm{3}})$ as a dopant source. A homoepitaxial diamond thin film with a thickness of about 300 nm was grown on the {111} surface of a type Ib diamond with a variety of dopant concentrations. Over a wide range of dopant concentrations (${\mathrm{PH}}_{\mathrm{3}}{\mathrm{/CH}}_{\mathrm{4}}\mathrm{:}$ 1000–20 000 ppm), the $n$ -type conduction was confirmed by Hall-effect measurements. The activation energy of carriers was 0.43 eV. The Hall mobility of about $\text{23\hspace{0.17em}}{\mathrm{cm}}^{\mathrm{2}}\mathrm{/V\hspace{0.17em}s}$ has been obtained at around 500 K for the 1000 ppm sample. No significant increase of hydrogen has been observed by secondary-ion-mass-spectroscopy analysis for the phosphorous doped layers.