Tuning band alignment at a semiconductor-crystalline oxide heterojunction via electrostatic modulation of the interfacial dipole

Abstract

We demonstrate that the interfacial dipole associated with bonding across the SrTiO3/Si heterojunction can be tuned through space charge, thereby enabling the 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 type-III. The transferred charge, resulting in 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.Functionalizing the interface dipole to enable electrostatic altering of band alignment opens new pathways to realize novel behavior in semiconducting heterojunctions.

Advanced Fabrication of 3D Micro/Nanostructures of Gallium Oxide with a Tuned Band Gap and Optical Properties

“…The formation of heterojunctions is a complex process, and includes factors such as the orientations of the crystal, the surface preparation, and the presence of defects and impurities [ 25 , 26 ]. Thus, it is hypothesized that the change is due to oxidation [ 27 , 28 ]. Having a thicker native layer affects the material’s VBO and CBO, leading to a change in the alignment.…”

Feld-induced modulation of two-dimensional electron gas at LaAlO3/SrTiO3 interface by polar distortion of LaAlO3

“…This work function difference (0.4 eV) is expected to introduce a Schottky barrier at the interface. The charged V O can result in the pinning of the Fermi level and/or lowering of the barrier height 45 , 46 , affecting the transport across the interface. The analysis of the I-V curves measured during in-situ STEM biasing experiments (Supplementary Fig.…”

First-Principles Investigation of Interfacial Reconstruction in Epitaxial SrTiO3/Si Photocathodes

“…This will certainly depend on the experimental conditions and oxygen chemical potential. However, in the case of a SrO interface (as sketched in Figure ), the configuration without dimers (Figure b, as reported in ref ) is only an unstable stationary point, and the stable configuration corresponds to a Si surface keeping dimer rows (Figure a), as previously reported by Zhang et al and Chrysler et al This stable structure is expected from the previous discussions since the ability to open Si dimers relies on the capacity of Sr to provide electrons to Si. In this case, Sr interfacial atoms will preferably provide electrons to O, much more electronegative, rather than to Si.…”