Tuning band alignment at a semiconductor-crystalline oxide heterojunctionvia electrostatic modulation of the interfacial dipole
ORAL
Abstract
Charge transfer across semiconductor heterojunctions and the electric fields that arise therefrom underpin the functionality of virtually all device technologies. In conventional semiconducting heterojunctions, band alignments are rigid under doping and charge transfer. In contrast, here we demonstrate that band alignment can be altered through charge transfer at hybrid heterojunctions comprised of crystalline oxides and semiconductors. The interfacial dipole associated with bonding across the SrTiO3/Si heterojunction can be tuned through space charge, thereby enabling band offsets and ultimately band alignment to be altered via doping. Oxygen impurities in Si act as donors that create space charge by transferring electrons across the interface into SrTiO3. The space charge induces an electric field that modifies the interfacial dipole, thereby tuning the band alignment from type II to III. The transferred charge, accompanying built-in electric fields, and change in band alignment are manifested in electrical transport and hard x-ray photoelectron spectroscopy measurements. Ab initio models reveal the interplay between polarization and band offsets. We find that band offsets can be tuned by modulating the density of space charge across the interface. Modulating the interface dipole to enable electrostatic altering of band alignment opens additional pathways to realize functional behavior in semiconducting hybrid heterojunctions.
2Diamond Light Source, Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
Diamond Light Source
Tien-Lin Lee
Diamond Light Source
Diamond Light Source, Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
Diamong Light Source
Aubrey Penn
Department of Materials Science & Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA
Bethany Matthews
Pacific Northwest National Laboratory
Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
Demie Kepaptsoglou
SuperSTEM, Daresbury, Warrington WA4 4AD, United Kingdom. Department of Physics, University of York, York YO10 5DD, United Kingdom
Quentin Ramasse
SuperSTEM, Daresbury, Warrington WA4 4AD, United Kingdom. School of Physics and Astronomy & School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, Un
Jay Paudel
Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
Raj Sah
Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
Joseph Grassi
Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
Zihua Zhu
Environmental Molecular Sciences Laboratory, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
Pacific Northwest National Laboratory
Alex X Gray
Temple University
Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
James M LeBeau
Massachusetts Institute of Technology
Department of Materials Science & Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
Steven Spurgeon
Pacific Northwest National Laboratory
Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
Scott Chambers
Pacific Northwest Natl Lab
Physical Sciences Division, Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
Peter Sushko
Physical Sciences Division, Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
