Effects of implantation energy and annealing temperature on the structural evolution of Ge+-implanted amorphous Si

High-resolution transmission electron microscopy in conjunction with autocorrelation function analysis have been applied to investigate the evolution of structural order in Ge+-preamorphized silicon layers. (001)Si wafers were preamorphized with 5 and 10 keV Ge+ to a dose of 5 x 10(15) ions/cm(2). A higher density of embedded nanocrystallites was found to be present in as-implanted amorphous Si layer for 10 keV Ge+ than that for 5 keV Ge+. The densities of embedded nanocrystallites in Ge+-preamorphized Si layer with 5 and 10 keV Ge+ were found to diminish with annealing temperature first then increase. The effects of ion-implantation energy and annealing temperature on the structural evolution in Ge+-implanted amorphous Si are discussed in terms of ion-beam induced annealing and free energy change of the system. The depth dependence on the density of embedded nanocrystallites is attributed to the nonuniform distribution of Ge atoms. (c) 2005 Elsevier B.V. All rights reserved.