ABSTRACT
For a semi-insulating GaAs single crystal containing very straight screw dislocations stretching over more than 100 μm in one direction, DC conductivity measurements were made from 300 K to 2.1 K in the direction parallel to the screw dislocation lines. Although the specimens were made thin enough (~20 μm) for a considerable portion of screw segments to penetrate the thickness, no change was detected in comparison with undeformed reference sample. Neither photoconductivity nor AC conductivity measurements indicated any distinct effect of dislocations. It is concluded that dislocation band states with sufficient width are not present in the bandgap, or the conduction paths if present are so frequently blocked that appreciable conduction is not easily detected.
