Formation of Ge dot or film in Ge/Si heterostructure by using sub-monolayer carbon deposition on top and in-situ post annealing

Effects of carbon (C) atoms on solid-phase epitaxial growth of Ge on Si(100) have been studied. C and Ge layers were deposited on Si(100) substrates at low temperature (150-300 °C) by using solid-source molecular beam epitaxy (MBE) system and subsequently annealed at 650 °C in the MBE chamber. The surface morphology after annealing changed depending on deposited amounts of C and deposition temperature of Ge. Ge dots were formed for small amounts of C while smooth Ge films were formed by large amounts of C varying with the Ge deposition temperature. The surface morphology after annealing was also affected by the as-deposited Ge crystallinity. The change in surface morphology depending on the amounts of deposited C was considered to be affected by the formation of Ge-C bonds which relieved the misfit strain between Ge and Si. The crystallinity of Ge deteriorated with increasing C coverage due to the incorporation of insoluble C atoms in the shape of both dots and films.