Effects of BF2 and B implantation-doping on crystalline degradation of pseudomorphic metastable Ge0.06Si0.94

Pseudomorphic metastable Ge0.06Si0.94 layers grown by molecular beam epitax y (MBE) on Si (100) substrates were implanted at room temperature by 70 keV BF2 ions with two different doses of 3 x 10(13) and 2.5 x 10(14) cm(-2), o r by 16 keV B ions with a dose of 4 x 10(14) cm(-2). The implanted samples were subsequently annealed at 800 and 900 degrees C for 30 min in a vacuum tube furnace. Observed by 2 MeV He-4 channeling spectrometry before anneali ng, only the sample implanted at a dose of 2.5 x 10(14) BS cm(-2) is amorph ized from surface to a depth of about 90 nm. Crystalline degradation of pos t-annealed Ge0.06Si0.94 samples becomes pronounced as the dose increases. E ven though the both samples implanted with 3 x 10(13) BF2 cm(-2) and 4 x 10 (14) B cm(-2) initially show almost the same levels of radiation damage in the channeling spectra, the sample implanted at 3 x 10(13) BF2 cm(-2) only conserves the same crystalline quality as the as-grown GeSi after being ann ealed. It is concluded that such a low dose of 3 x 10(13) BF2 cm(-2) can be doped by implantation without causing radiation or strain-induced defects in the pseudomorphic GeSi.