Effect of Light on the Mobility of Dislocations in Germanium

Dislocation velocity measurements have been made from observations of dislocation rosette growth during annealing of germanium containing Knoop hardness indentations. Dislocation velocities followed the relation v=v* exp(−ΔH/kT) exp(−X/X0), where X is the length of the semimajor axis of the rosette. At annealing temperatures below 300°C, the activation enthalpies ΔH were 1.0–1.3 eV, and v* ranged from 103 to 106 cm/sec for samples annealed in darkness while ΔH decreased to 0.55–0.8 eV and v* to 10−1−102 cm/sec for samples annealed under infrared illumination. At annealing temperatures above 300°C, ΔH was 0.35–0.40 eV and v* 10−3 cm/sec, independent of illumination. An hypothesis based on Read's model of dislocation in germanium accounts qualitatively for most of the observed phenomena.