$n$-type conductivity in ultrananocrystalline diamond films

Hall effect measurements have been carried out to determine the carrier density and mobilities in ultrananocrystalline diamond films grown with added nitrogen. The results show clear $n$-type conductivity with very low thermal activation energy. Mobility values of $1.5cm2V−1s−1$ are found for a sheet carrier concentration of $2×1017cm−2$⁠. These measurements indicate that ultrananocrystalline films grown with high nitrogen levels in the growth gas mixture can have bulk carrier concentrations of up to $1021$⁠, which is very high for diamond films. The $n$-type nature of this material was also confirmed by Seebeck effect measurements.