Formation of twist boundaries in germanium deformed in torsion

Abstract

Abstract Germanium single crystals of [111] orientation were deformed in torsion at several temperatures to various specific angles φ 0 [deg/cm]. Slip lines showed the deformation to occur only on (111) planes. The plastic torsion was stable with annealing up to 900 °C. Electron transmission showed that (111) twist boundaries with hexagonal dislocation networks are formed already during deformation at 685 °C. The percentage of network dislocations increased with φ 0 and with the temperature of annealing. The fraction of screw dislocations increased by 15% during an anneal up to a total of about 80%. The dislocation arrangement after annealing closely corresponds to theoretical expectations.