Dosage dependence of Ge quantum dots grown on carbon-implanted Si substrates

Abstract

Carbon implantation effects on self-assembled Ge quantum dots (QDs) have been investigated. Carbon atoms were implanted at different dosage, 9.0×10 14, 4.5×10 15, and 9.0×10 15 ions/cm 2 using the same acceleration energy of 20 keV. A nominal amount, 6 monolayer (ML), of Ge was grown on the substrate at different growth temperatures ranging from 500 to 600 °C using solid source molecular beam epitaxy. The smallest Ge QDs with a 13 nm mean lateral diameter, a 1.2 nm mean height, and an areal density of 2.0×10 11 cm −2 were obtained using the lowest dosage substrate at 550 °C. Raman measurement is carried out to investigate the optical phonons and strain.