HREM studies of twins in Cd_(1-x)Zn_xTe (x approx = 0.04) thin films grown by molecular beam epitaxy

摘要

The microstructure of ferroelectric Cd_(1-x)Zn_xTe (CZT) thin films with x approx = 0.04 grown by molecular beam epitaxy has been studied by means of cross sectional high-resolution transmission electron microscopy (HREM). High-density {111} lamellar twins are found to be the dominant defects in the films. Double-position twins with twin boundaries nearly parallel to (11 -2) are observed to always coexist with the (111) 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 (111) twins in the ferroelectric CZT layer are shorter than those in the Cd_(1-x)Zn_xTe buffer layers is explained. The films show uniform texture direction oriented along [111] except a few regions with the habit faces of twins oblique to the surface of the films.