DISLOCATIONS AND QUANTUM TRANSPORT - A POSSIBLE HINT FOR ONE-DIMENSIONAL CONDUCTIVITY ALONG DISLOCATION LINES - A FUNDAMENTAL MECHANISM FORTHE EBIC CONTRAST FORMATION

Models of the electron-beam-induced current (EBIC) contrast including physical properties of dislocations were recently proposed, on the bas is of the existence of an electron field surrounding the dislocation f ines. In these elemental models, as it is assumed that there is minori ty-carrier capture by these electrical fields, the dislocation recombi nation efficiency is finally determined by the majority-carrier captur e mechanism. To obtain theoretical results comparable with experimenta l data, it was suggested that the majority-carrier capture could not b e regulated by thermally overcoming the dislocation potential (which l eads to too small values of the EBIC contrast) but would rather corres pond to a possible electrical current along the dislocation lines. In order to give further evidence of the existence of such electrical cur rents along dislocations, we have measured the transport behaviour of quantum wells containing straight dislocations. The analysis of our ex perimental results show that dislocations induce a strong anisotropy o f the two-dimensional (2D) layer conductivity and that, in given dislo cation substructures, the 2D electron gas behaviour is no longer purel y conserved. We suggest that these results provide a further hint as t o the existence of some electrical conductivity along the dislocation lines.