title: Photo-induced persistent inversion of germanium in a 200-nm-deep surface region.
abstract: The controlled manipulation of the charge carrier concentration in nanometer thin layers is the basis of current semiconductor technology and of fundamental importance for device applications. Here we show that it is possible to induce a persistent inversion from n- to p-type in a 200-nm-thick surface layer of a germanium wafer by illumination with white and blue light. We induce the inversion with a half-life of ~12 hours at a temperature of 220 K which disappears above 280 K. The photo-induced inversion is absent for a sample with a 20-nm-thick gold capping layer providing a Schottky barrier at the interface. This indicates that charge accumulation at the surface is essential to explain the observed inversion. The contactless change of carrier concentration is potentially interesting for device applications in opto-electronics where the gate electrode and gate oxide could be replaced by the semiconductor surface.
authors.affiliation: Paul Scherrer Institute, Laboratory for Muon Spin Spectroscopy, Villigen PSI, Switzerland. thomas.prokscha@psi.ch
authors.forename: T
authors.initials: T
authors.lastname: Prokscha
authors.forename: K H
authors.initials: KH
authors.lastname: Chow
authors.forename: E
authors.initials: E
authors.lastname: Stilp
authors.forename: A
authors.initials: A
authors.lastname: Suter
authors.forename: H
authors.initials: H
authors.lastname: Luetkens
authors.forename: E
authors.initials: E
authors.lastname: Morenzoni
authors.forename: G J
authors.initials: GJ
authors.lastname: Nieuwenhuys
authors.forename: Z
authors.initials: Z
authors.lastname: Salman
authors.forename: R
authors.initials: R
authors.lastname: Scheuermann
mesh_terms: D005857:Germanium / Q000737:chemistry* / Q000528:radiation effects*; D008027:Light; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000528:radiation effects*; D012666:Semiconductors; D013499:Surface Properties; D013696:Temperature
chemical_list: D005857:Germanium