Studies of dislocation loops produced by irradiation of ZnO in a high-voltage electron microscope

Abstract

Electron-irradiation studies on vapour-grown ZnO ribbon crystals have been carried out in situ in a high-voltage electron microscope. Dislocation loops nucleate both on stacking-fault planes and in the matrix by irradiation with electron accelerated through voltages higher than 700 kV at room temperature. Two types of loops with the Burgers vectors b = 1/2c and b = a exist in the matrix, where a = 1/3<2110> and c = [0001]. On the other hand, loops with b = 1/2 c + a/3 and those with b = 1/2c are formed on the prismatic fault planes and basal fault planes, respectively. Diffraction-contrast experiments show these loops to be of interstititial type. A re-irradiation experiment after the annealing indicates a possibility that there exist vacancies in the matrix at 700°C.