TRANSMISSION ELECTRON-MICROSCOPY INVESTIGATION OF THE RECRYSTALLIZATION OF AN AMORPHOUS LAYER IN SI+-IMPLANTED SILICON

The recrystallization of a buried amorphous layer in p-type (111) float zone silicon implanted at room temperature with a dose of 2 X 10(15) cm-2 100 keV Si+ ions is studied between room temperature and 1200-degrees-C by transmission electron microscopy. A 150-nm-thick amorphous layer is created by ion implantation below a 25-nm-thick surface layer, which remains crystalline. Below the amorphous layer small defects are observed, which form well-resolved dislocation loops after annealing at higher temperatures. At 700-degrees-C, one nearly defect-free layer grows from the microcrystalline surface layer up to a depth of 40 nm and another nearly defect-free layer grows from the crystalline-amorphous interface up to a thickness of 25 nm. Between these two layers the sample recrystallizes by forming a 110-nm-thick layer containing a high density of microtwin lamellae. In the top layer up to a depth of 40 nm some stacking-fault tetrahedra are formed by epitaxial regrowth from the surface. After annealing at higher temperatures only the sizes of the structural defects increase.