Hole Transport in Pure NiO Crystals

The drift mobility of excess holes has been investigated in undoped NiO crystals using a transient technique with electron-beam excitation. Specimens with low-impurity content were grown epitaxially from the gas phase. At room temperature ${\mu }_h$ lies between 20 and 50 ${\mathrm{cm}}^2$ ${\mathrm{V}}^{-1\mathrm{}}$ ${\sec }^{-1\mathrm{}}$, and its temperature dependence shows that scattering by optical modes predominates. The results lead to a phonon energy of 0.055 eV, a polaron effective mass of $1.5m_0$, and a coupling constant of 1.6.