Formation mechanisms of ZnO nanocrystals embedded in an amorphous Zn2xSi1-xO2 layer due to sputtering and annealing

Abstract

ZnO nanocrystals embedded in an amorphous Zn2xSi1-xO2 layer inserted between a ZnO thin film and a p-Si (100) substrate were formed by magnetron sputtering and thermal annealing. High-resolution transmission electron microscopy (HRTEM) images showed that ZnO nanocrystals were embedded in the Zn2xSi1-xO2 layer inserted into a ZnO/Si heterostructure. The {01 (1) over bar0} planes were observed for the ZnO nanocrystals with a [0001] orientation direction, and the {01 (1) over bar1} and the {0001} planes were observed for the ZnO nanocrystal with a [2 (1) over bar(1) over bar0] orientation direction. The formation of ZnO nanocrystals consisting of the most stable {0001} and (01 (1) over bar1) facet planes was attributed to atomic rearrangement of Zn and 0 atoms to reduce the surface energy during the thermal annealing and the cooling processes. The formation mechanisms for the ZnO nanocrystals embedded in an amorphous Zn2xSi1-xO2 layer inserted into a ZnO/p-Si (100) heterostructure were described on the basis of the HRTEM images. (C)2010 Elsevier B.V. All rights reserved.