Solid-phase epitaxial growth of Ge-Si alloys made by ion implantation

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Abstract
Solid‐phase epitaxial growth was studied in germanium‐implanted 〈100〉 silicon wafers as a function of germanium fluence, annealing temperature, and time. MeV He Rutherford backscattering in channeling conditions, cross‐sectional transmission electron microscopy, double‐crystal x‐ray diffraction, and secondary‐ion mass spectroscopy techniques were used to characterize the samples. At low fluences, up to 1×1015 cm−2 at 130 keV, the crystallization kinetics is similar to that measured on self‐amorphized silicon. In the high‐dose samples, prepared by multiple implants with a total dose of 3.12×1016 cm−2, the growth rate at fixed temperatures decreases. A comparison with literature data, obtained by similar experiments performed on amorphized uniform GexSi100−x films prepared by molecular‐beam epitaxy or chemical‐vapor deposition, reveals that the concentration gradient, unavoidable in implanted samples mainly at the end of the ion range region, is strictly connected with the observed decrease.