PRECIPITATION IN HEAVILY ARSENIC-IMPLANTED GEXSI1-X ALLOYS

We report a study of precipitation and diffusion in Ge0.5Si0.5 alloy implanted with As+ ions at an energy of 100 keV with a dose of 6×1016cm-2 and subsequently annealed at 800 and 1000°C for 1 h. The samples were analyzed by transmission electron microscopy and x-ray energy dispersive spectrometry. A high density of precipitates was observed near the surface of the samples after annealing both at 800 and 1000°C. The behavior of the precipitation is strongly dependent on the anneal temperature. When the anneal temperature increases, the average size of precipitates increases and the distribution of the precipitates is localized in the vicinity of the surface. X-ray spectra show that most of the largest precipitates formed during the annealing are arsenides. Rodlike precipitates formed during the thermal annealing at 800°C are tentatively identified as monoclinic GeAs by selected electron diffraction patterns.© 1995 American Institute of Physics.