title: Ultrafast dynamics. Attosecond band-gap dynamics in silicon.
abstract: Electron transfer from valence to conduction band states in semiconductors is the basis of modern electronics. Here, attosecond extreme ultraviolet (XUV) spectroscopy is used to resolve this process in silicon in real time. Electrons injected into the conduction band by few-cycle laser pulses alter the silicon XUV absorption spectrum in sharp steps synchronized with the laser electric field oscillations. The observed ~450-attosecond step rise time provides an upper limit for the carrier-induced band-gap reduction and the electron-electron scattering time in the conduction band. This electronic response is separated from the subsequent band-gap modifications due to lattice motion, which occurs on a time scale of 60 ± 10 femtoseconds, characteristic of the fastest optical phonon. Quantum dynamical simulations interpret the carrier injection step as light-field-induced electron tunneling.
authors.affiliation: Department of Chemistry, University of California, Berkeley, CA 94720, USA. Fakultät für Physik, Ludwig-Maximilians-Universität, Am Coulombwall 1, D-85748 Garching, Germany. martin.schultze@mpq.mpg.de dneumark@berkeley.edu srl@berkeley.edu.
authors.forename: Martin
authors.initials: M
authors.lastname: Schultze
authors.affiliation: Department of Chemistry, University of California, Berkeley, CA 94720, USA.
authors.forename: Krupa
authors.initials: K
authors.lastname: Ramasesha
authors.affiliation: The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: C D
authors.initials: CD
authors.lastname: Pemmaraju
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Japan.
authors.forename: S A
authors.initials: SA
authors.lastname: Sato
authors.affiliation: Department of Chemistry, University of California, Berkeley, CA 94720, USA.
authors.forename: D
authors.initials: D
authors.lastname: Whitmore
authors.affiliation: Department of Chemistry, University of California, Berkeley, CA 94720, USA.
authors.forename: A
authors.initials: A
authors.lastname: Gandman
authors.affiliation: Department of Chemistry, University of California, Berkeley, CA 94720, USA.
authors.forename: James S
authors.initials: JS
authors.lastname: Prell
authors.affiliation: Department of Chemistry, University of California, Berkeley, CA 94720, USA.
authors.forename: L J
authors.initials: LJ
authors.lastname: Borja
authors.affiliation: The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: D
authors.initials: D
authors.lastname: Prendergast
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Japan. Center for Computational Sciences, University of Tsukuba, Tsukuba 305-8577, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yabana
authors.affiliation: Department of Chemistry, University of California, Berkeley, CA 94720, USA. Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. martin.schultze@mpq.mpg.de dneumark@berkeley.edu srl@berkeley.edu.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Neumark
authors.affiliation: Department of Chemistry, University of California, Berkeley, CA 94720, USA. Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. Department of Physics, University of California, Berkeley, CA 94720, USA. martin.schultze@mpq.mpg.de dneumark@berkeley.edu srl@berkeley.edu.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Leone