Hole Mobility in Boron-Doped Homoepitaxial CVD Diamond Thin Films

The electric conductivity and Hall effect of boron-doped homoepitaxial CVD diamond thin films have been measured in the temperature range from 150K to 900 K. The temperature dependence of Hall mobility is analyzed by using an iterative technique assuming the scattering by ionized impurities, acoustic deformation potential and nonpolar optical phonons. The acoustic deformation potential constant EI, the coupling constant of nonpolar optical phonons Dnpo and the donor concentration ND are used as fitting parameters. We take into account the band nonparabolicity through the hyperbolic band model. The density of state mass md, the conduction mass mc) and the nonparabolicity parameter alpha are estimated from a LAPW band calculation. The temperature dependence of hole concentration is also numerically analyzed on the basis of the electric neutrality and the hyperbolic band model with fitting parameters of the acceptor concentration NA, the donor concentration ND, and the acceptor ionization energy EA. For all the samples, best fits between experimental and theoretical values are obtained when EI approx. 16.0 eV, Dnpo approx. 1.2x1012 eV/m and EA approx. 0.365 eV. Some indications of the impurity conduction were seen in the low temperature range.