Transmission electron microscopy study of crystal defects in ZnSe/GaAs(001) epilayers

ZnSe thin films grown on GaAs(001) substrate by molecular beam epitaxy to a thickness of 2500 A have been studied by transmission electron microscopy (TEM). Three types of structural defect have been observed: (i) Triangle-sh aped stacking faults, with the apex close to the interface, either isolated or paired. They are bounded by two different Shockley dislocations. (ii) S tacking faults generated from the surface of the ZnSe epilayer by movement of a Shockley half-loop. (iii) An array of perfect misfit dislocations. The ir Burgers vectors are inclined to the interface. Most of them lie along [3 10] directions; only a few are parallel to [110].