Hall Mobility of Positive Holes in Cu₂O

Hall mobility of photoexcited holes in the \(\varGamma_{7}^{+}\) valence band of Cu ₂ O has been measured at low temperatures. On the basis of the theory of carrier-lattice interactions in polyatomic crystals the intrinsic scattering mechanisms of this substance have been clarified, for the first time, in a wide temperature range up to 400 K. From 40 K to 100 K scattering is dominated by the low-frequency LO phonon, ω ₁ . Above 100 K, the effect of the high-frequency LO phonon, ω ₂ , becomes remarkable. Here, ω ₁ =153 cm ^-1 and ω ₂ =660 cm ^-1 at 4.2 K. Mobility quenching due to the metastable self-trapping of holes possibly underlies the phenomena above 200 K. Below 40 K, the temperature dependence of mobility can be explained in terms of a combination of the effects of optical, acoustical and neutral impurity scatterings. The magnitude of the deformation potential of the \(\varGamma_{7}^{+}\) valence band is estimated to be as small as 0.7±0.3 eV.