The growth of strained Si_1−xGe_x alloys on 〈001〉 silicon using solid phase epitaxy

Abstract

In this paper we report on the growth of pseudomorphically strained Si_1−xGe_x alloys on 〈001〉 Si by solid phase epitaxy. One set of amorphous alloys was formed by high dose ion implantation ⁷⁴Gc implanted at an energy of 200 kcV to a fluence of 9.6 ⊠ 10²⁰/m²). Our TEM observations show that regrowth of these Si_1−xGe_x(x_max = 0.14) films at ≍590°C results in a high density of planar defects and that these defects are associated with faceting of the amorphous/crystalline interface during annealing. These results were compared with the solid phase regrowth of MBE-grown Si_0.7Ge_0.3 amorphized with 170 keV ²⁸Si ions which exhibited identical defects and faceting during regrowth. Attendant with this faceting was a decrease in the regrowth velocity, a result of a change from a planar {001} growth morphology to a multi-faceted growth surface containing many <50 nm deep pyramidal impressions. The regrowth rate was quantified, at a particular temperature, by the use of Si homoepitaxy for calibration of in situ TEM experiments. It was shown that the regrowth rate at 594°C in pure Si was 51 nm/min, whereas in the Si_0.7Ge_0.3 the regrowth rate decreased, as a result of {111} faceting, to 21 nm/min. RBS was used to characterize Ge concentrations and lattice resolution TEM was used to study the development of the faceted interface and associated planar defects during regrowth.