Transmission electron microscopy in situ investigation of dislocation mobilities in inp

Several dislocations sources were observed in indium phosphide (InP) single crystal, at 623 K, by transmission electron microscopy (TEM) in situ straining of thin foils, at 200 kV. For this temperature and under a given stress, the emitted loops are composed of linear parts (indicating a strong lattice friction) which are the three types of dislocation lines present in this kind of material: screw, 60[ddot]α and 60[ddot]β. The velocity of all types, for a constant local stress, is found to be proportional to the dislocation length (L) for low L. Within the experimental conditions no maximum velocity is noticed, as in GaAs (Caillard, Clément, Couret, Androussi, Lefebvre and Vanderschaeve 1989). We find, at fixed length, that 60[ddot] α are faster than screws and 60[ddot]β, the latter two having similar velocities. The velocity-length curve is used to estimate the range of activation energies, through the Hirth and Lothe model (Hirth and Lothe 1968), for kink formation (F dk ) and migration (W m ) on screw dislocations.