Positron Mobility in Diamond

Abstract

The mobility of a thermal positron in diamond is studied theoretically and experimentally. An approximate wave function of a positron is obtained by the Wigner-Seitz method for an effective hard sphere potential with radius determined by the WKB method. The dilatation due to the acoustic wave gives rise to a change in the energy determined as a function of the Wigner-Seitz cell radius, which yields the positron-phonon interaction of the deformation potential type. The estimated mobility has ambiguities but may have the order of magnitude 50∼500 cm²/volt · sec. The experimental value of the mobility obtained by means of the angular correlation in positron annihilation is less than 20 cm²/volt · sec at room temperature, much smaller than the mobility 1200 cm²/volt · sec of a hole in the valence band.