title: High-k gate stacks on low bandgap tensile strained Ge and GeSn alloys for field-effect transistors.
abstract: We present the epitaxial growth of Ge and Ge0.94Sn0.06 layers with 1.4% and 0.4% tensile strain, respectively, by reduced pressure chemical vapor deposition on relaxed GeSn buffers and the formation of high-k/metal gate stacks thereon. Annealing experiments reveal that process temperatures are limited to 350 °C to avoid Sn diffusion. Particular emphasis is placed on the electrical characterization of various high-k dielectrics, as 5 nm Al2O3, 5 nm HfO2, or 1 nmAl2O3/4 nm HfO2, on strained Ge and strained Ge0.94Sn0.06. Experimental capacitance-voltage characteristics are presented and the effect of the small bandgap, like strong response of minority carriers at applied field, are discussed via simulations.
authors.affiliation: Peter Grünberg Institute (PGI 9) and JARA-FIT , Forschungszentrum Jülich, 52425 Jülich, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Wirths
authors.forename: Daniela
authors.initials: D
authors.lastname: Stange
authors.forename: Maria-Angela
authors.initials: MA
authors.lastname: Pampillón
authors.forename: Andreas T
authors.initials: AT
authors.lastname: Tiedemann
authors.forename: Gregor
authors.initials: G
authors.lastname: Mussler
authors.forename: Alfred
authors.initials: A
authors.lastname: Fox
authors.forename: Uwe
authors.initials: U
authors.lastname: Breuer
authors.forename: Bruno
authors.initials: B
authors.lastname: Baert
authors.forename: Enrique
authors.initials: E
authors.lastname: San Andrés
authors.forename: Ngoc D
authors.initials: ND
authors.lastname: Nguyen
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Hartmann
authors.forename: Zoran
authors.initials: Z
authors.lastname: Ikonic
authors.forename: Siegfried
authors.initials: S
authors.lastname: Mantl
authors.forename: Dan
authors.initials: D
authors.lastname: Buca
keywords: GeSn; field effect transistor; high-k dielectrics; low bandgap alloys; strained Ge