The integration of dissimilar materials is highly desirable for many different types of device applications but often challenging to achieve in practice. The unrivalled imaging capabilities of the aberration-corrected electron microscope enable enhanced insights to be gained into the atomic arrangements across heterostructured interfaces. This paper provides an overview of our recent observations of oxide-semiconductor heterostructures using aberration-corrected high-angle annular-dark-field and large-angle bright-field imaging modes. The perovskite oxides studied include strontium titanate, barium titanate, and strontium hafnate, which were grown on Si(001) and/or Ge(001) substrates using the techniques of molecular-beam epitaxy or atomic-layer deposition. The oxide layers displayed excellent crystallinity and sharp, abrupt interfaces were observed with no sign of any amorphous interfacial layers. The Ge(001) substrate surfaces invariably showed both 1× and 2× periodicity consistent with preservation of the 2 × 1 surface reconstruction following oxide growth. Overall, the results augur well for the future development of functional oxide-based devices integrated on semiconductor substrates.
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This work has primarily been supported by the Air Force Office of Scientific Research through Grants FA9550-12-10494 and FA9550-14-10090 and the National Science Foundation Award CMMI-1437050. The authors gratefully acknowledge the use of facilities in the John M. Cowley Center for High Resolution Electron Microscopy at Arizona State University.
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Smith, D.J., Wu, H., Lu, S. et al. Recent studies of oxide-semiconductor heterostructures using aberration-corrected scanning transmission electron microscopy. Journal of Materials Research 32, 912–920 (2017). https://doi.org/10.1557/jmr.2016.273