Study on the Twin Formation in Evaporated Silver Films

Abstract

Well oriented silver films have been formed by evaporation onto heated cleavage (001) surfaces of rock-salt in vacuum, the evaporation period having been changed in a wide range in case of the thickness kept at about 400 A, and the influence of the formation speed on the twinning in the films has been examined by electron diffraction and electron microscopy. The diffraction patterns have shown that the frequency of the twin formation is not seriously decreased by the lowest formation speed, but that imperfections such as bending or twisting of films are largely decreased. The interference fringes caused by the dynamical effect have been observed on the electron micrographs of slowly formed films. This fact means that the slow formation of films decreases also imperfections such as dislocations and vacancies and makes the lattice more perfect. The fringes are believed to be so-called equal thickness fringes originated from wedges due to the twin formation.