Cross‐Sectional Scanning Tunneling Microscopy Applied to Complex Oxide Interfaces

Abstract

Understanding interfacial science is critical to many modern technologies. It is very common in solid‐state physics for electronic properties to show novel phenomena when combining various dissimilar materials at atomically abrupt interfaces. For example, semiconductor interfaces have provided the foundation of modern electronic devices for several decades. Now with advances in growth and synthesis, controllable high quality complex oxide heterojunctions can be routinely fabricated. Since complex oxide materials exhibit a wide variety of functionalities owing to their strong coupling to the electron, lattice, orbital and spin degrees of freedom, these materials display a wide spectrum of interesting functionalities. Combining dissimilar complex oxides at interfaces allows one to explore and create intriguing phenomena that are not attainable in the lone bulk constituents. However, the key challenge has been the direct characterization of these interfaces at the nanoscale in order to understand the physical properties found at complex oxide interfaces. This requires the development of new experimental approaches. In this paper, we review the utilization of cross‐sectional scanning tunneling microscopy/spectroscopy as a direct probe of these oxide interfaces at the nanoscale. This technique provides valuable insight to both structural and electronic properties of these unique systems and enables understanding of the detailed electronic structure (e.g., local electronic density of states (LDOS), charge transfer, band bending, etc.) at oxide interfaces, which is of key interest to both fundamental and applied science.

Surface Termination-Dependent Nanotribological Properties of Single-Crystal MAPbBr3 Surfaces

“…Indeed, we mostly observed the disordered island feature when the size of the terrace exceeded ∼1 μm (see Figure S1 for an example). It is worth noting that the formation of distinctive surface domains and the agglomeration to disordered islands after cleavage is consistent with the surface morphology of as-cleaved oxide perovskite single crystals without strongly preferred cleavage planes. − Figure a,b shows the images of the topography and lateral force (trace), respectively, that were obtained simultaneously. The line profiles along the red and blue lines in the topography and lateral force images, respectively, are shown in Figure c.…”

Coexistence of Two Electronic Nano-Phases on a CH3NH3PbI3–xClx Surface Observed in STM Measurements

“…And are there any other types of phase separation in the film due to local I or Cl segregation? To obtain deeper understanding regarding these questions, cross-sectional STM/S (XSTM/S) is utilized. − XSTM/S is used to create a fresh perovskite surface for STM measurements. Other sample preparation methods, such as sputtering/annealing, are expected to change the highly sensitive perovskite materials.…”

Oxygen vacancies on SrO-terminatedSrTiO3(001)surfaces studied by scanning tunneling spectroscopy

“…2, takes the form of greater roughness on the TiO 2 -terminated surface. The two terminations can be reliably distinguished if one knows the difference in local density of states between the terminations at a particular sample bias [32,35,36]. A bright stripe seen in a conductance map acquired with a sample bias of +3.0 V generally signifies SrO termination while a dark stripe signifies TiO 2 termination.…”

“…PACS: 68. 35.Dv, 68.37.Ef, 68.47.Gh Subject Areas: Condensed Matter Physics, Scanning Tunneling Microscopy, Computational Physics…”