By using weak-beam dark-field transmission electron microscopy, an additional crystal defect was identified as well as stacking fault trapezoids. This was a stacking-fault tetrahedron at the interface of the ZnSe/GaAs(001) epilayers. Unlike other stacking faults, which were essentially of uniform size, the size of these stacking fault tetrahedra could vary by a few fold, with a typical value of less than 10nm. The stacking-fault tetrahedron was a closed defect and did not extend very far from the interface. The density of the stacking-fault tetrahedra was at least as high as that of the predominant stacking-fault trapezoids.

K.K.Fung, N.Wang, I.K.Sou: Applied Physics Letters, 1997, 71[9], 1225-7