title: Strongly Metallic Electron and Hole 2D Transport in an Ambipolar Si-Vacuum Field Effect Transistor.
abstract: We report experiment and theory on an ambipolar gate-controlled Si(111)-vacuum field effect transistor where we study electron and hole (low-temperature 2D) transport in the same device simply by changing the external gate voltage to tune the system from being a 2D electron system at positive gate voltage to a 2D hole system at negative gate voltage. The electron (hole) conductivity manifests strong (moderate) metallic temperature dependence with the conductivity decreasing by a factor of 8 (2) between 0.3 K and 4.2 K with the peak electron mobility (∼18  m2/V s) being roughly 20 times larger than the peak hole mobility (in the same sample). Our theory explains the data well using random phase approximation screening of background Coulomb disorder, establishing that the observed metallicity is a direct consequence of the strong temperature dependence of the effective screened disorder.
authors.affiliation: Laboratory for Physical Sciences, University of Maryland, College Park, Maryland 20740, USA.|Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Binhui
authors.initials: B
authors.lastname: Hu
authors.affiliation: Laboratory for Physical Sciences, University of Maryland, College Park, Maryland 20740, USA.|Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Yazdanpanah
authors.affiliation: Laboratory for Physical Sciences, University of Maryland, College Park, Maryland 20740, USA.|Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: B E
authors.initials: BE
authors.lastname: Kane
authors.affiliation: Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA.|Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA.|SKKU Advanced Institute of Nanotechnology and Department of Physics, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: E H
authors.initials: EH
authors.lastname: Hwang
authors.affiliation: Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA.|Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA.
authors.forename: S
authors.initials: S
authors.lastname: Das Sarma