SYNTHESIS OF OXIDES IN SI05GE05 ALLOY BY HIGH-DOSE OXYGEN ION-IMPLANTATION

A Si0.5Ge0.5 alloy layer was implanted at a temperature of about 500-degrees-C with doses of 0.6 x 10(18), 1.2 x 10(18) and 1.8 x 10(18) O+ cm-2 at an energy of 200 keV. The alloy layer was prepared by molecular beam epitaxy (MBE), with an 800 nm thick film of Si0.5Ge0.5 alloy followed by a 75 nm thick top silicon layer grown on an n-type Si(100) (rho = 5-20 OMEGA cm) substrate. X-ray photoelectron spectroscopy measurements and Rutherford backscattering indicated that Si-O and Ge-O compounds were formed during the oxygen bombardment. The sample implanted with a dose of 1.8 x 10(18) O+ cm-2 was annealed at a temperature of 1000-degrees-C, which caused further growth of the SiO2 phase with a concomitant reduction in the oxides of germanium and rejection of germanium from the synthesis layer. The different oxidation rates for silicon and germanium can be attributed to thermodynamic effects.