HREM studies of twins in Cd1−xZnxTe (x ≈ 0.04) thin films grown by molecular beam epitaxy

The microstructure of ferroelectric Cd1−xZnxTe (CZT) thin films with x ≈ 0.04 grown by molecular beam epitaxy has been studied by means of cross sectional high-resolution transmission electron microscopy (HREM). High- density {1 1 1} lamellar twins are found to be the dominant defects in the films. Double-position twins with twin boundaries nearly parallel to (1 1 −2) are observed to always coexist with the (1 1 1) lamellar twins and stop the penetration of the latter. The coexistence of both kinds of twins produces complex twin structures with triple-point and quadruple-point junctions. The fact that lamellar (1 1 1) twins in the ferroelectric CZT layer are shorter than those in the Cd1−xMgxTe buffer layers is explained. The films show uniform texture direction oriented along [1 1 1] except a few regions with the habit faces of twins oblique to the surface of the films.