title: Self-organized superlattice formation during crystal growth from continuous beam fluxes.
abstract: Alloy superlattice structures consisting of alternating Si-rich and C-rich layers form spontaneously during gas-source molecular beam epitaxy of Si(1-y)C(y) on Si(001) from constant Si2H6 and CH3SiH3 precursor fluxes at T(s)=725-750 degrees C. The self-organized patterning is due to a complex interaction among competing surface reactions. During growth of the initial Si-rich layer, strain-driven C segregation to the subsurface results in charge transfer from surface Si atom dangling bonds to C backbonds. This decreases the Si2H6 sticking probability, and, hence, the instantaneous deposition rate, thereby enhancing C segregation. The Si-rich layer continues until a critical C coverage is reached allowing nucleation of a C-rich layer which grows until the excess subsurface C is depleted. The process then repeats with periods tunable through the choice of T(s) and y(avg).
authors.affiliation: Frederick Seitz Materials Research Laboratory and the Materials Science Department, University of Illinois, 104 South Goodwin Avenue, Urbana, IL 61801, USA.
authors.forename: Y L
authors.initials: YL
authors.lastname: Foo
authors.forename: K A
authors.initials: KA
authors.lastname: Bratland
authors.forename: B
authors.initials: B
authors.lastname: Cho
authors.forename: C W
authors.initials: CW
authors.lastname: Lim
authors.forename: J
authors.initials: J
authors.lastname: Baker
authors.forename: J G
authors.initials: JG
authors.lastname: Wen
authors.forename: D W
authors.initials: DW
authors.lastname: Moon
authors.forename: J E
authors.initials: JE
authors.lastname: Greene