Doping the Undopable: Hybrid Molecular Beam Epitaxy Growth, n-Type Doping, and Field-Effect Transistor Using CaSnO3

Fengdeng Liu, Prafful Golani, Tristan K. Truttmann, Igor Evangelista, Michelle A. Smeaton, David Bugallo, Jiaxuan Wen, Anusha Kamath Manjeshwar, Steven J. May, Lena F. Kourkoutis, Anderson Janotti, Steven J. Koester, Bharat Jalan

Research output: Contribution to journalArticlepeer-review


The alkaline earth stannates are touted for their wide band gaps and the highest room-temperature electron mobilities among all of the perovskite oxides. CaSnO3 has the highest measured band gap in this family and is thus a particularly promising ultrawide band gap semiconductor. However, discouraging results from previous theoretical studies and failed doping attempts had described this material as “undopable”. Here we redeem CaSnO3 using hybrid molecular beam epitaxy, which provides an adsorption-controlled growth for the phase-pure, epitaxial, and stoichiometric CaSnO3 films. By introducing lanthanum (La) as an n-type dopant, we demonstrate the robust and predictable doping of CaSnO3 with free electron concentrations, n3D, from 3.3 × 1019 cm-3 to 1.6 × 1020 cm-3. The films exhibit a maximum room-temperature mobility of 42 cm2 V-1 s-1 at n3D = 3.3 × 1019 cm-3. Despite having a comparable radius as the host ion, La expands the lattice parameter. Using density functional calculations, this effect is attributed to the energy gain by lowering the conduction band upon volume expansion. Finally, we exploit robust doping by fabricating CaSnO3-based field-effect transistors. The transistors show promise for CaSnO3’s high-voltage capabilities by exhibiting low off-state leakage below 2 × 10-5 mA/mm at a drain-source voltage of 100 V and on-off ratios exceeding 106. This work serves as a starting point for future studies on the semiconducting properties of CaSnO3 and many devices that could benefit from CaSnO3’s exceptionally wide band gap.

Original languageEnglish (US)
Pages (from-to)16912-16922
Number of pages11
JournalACS nano
Issue number17
StatePublished - Sep 12 2023

Bibliographical note

Funding Information:
The work was primarily supported by the Air Force Office of Scientific Research (AFOSR) through grants FA9550-19-1-0245, FA9550-21-1-0025, and FA9550-21-0460. We acknowledge partial support from the National Science Foundation (NSF) through award number DMR-2306273. We (S.J.K., B.J., and S.J.M.) also acknowledge partial support from the NSF through the Future of Semiconductor teaming grant (FuSe-TG) (award no. DMR - 2235208). Film growth was performed using instrumentation funded by AFOSR DURIP award FA9550-18-1-0294. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from the NSF through the MRSEC (award no. DMR-2011401). Portions of this work were carried out at the Minnesota Nano Center, which receives support from the NSF through the National Nanotechnology Coordinated Infrastructure (NNCI) under award no. ECCS-2025124. D.B. acknowledges the funding received from the European Union through the Marie Skłodowska-Curie Actions Postdoctoral Fellowship (ref 101063432). Transmission electron microscopy work was supported by the NSF [Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM)] under Cooperative Agreement No. DMR-2039380 and made use of the Cornell Center for Materials Research (CCMR) Shared Facilities, which are supported through the NSF MRSEC Program (DMR-1719875). M.A.S. acknowledges support from the NSF GRFP (DGE-2139899). I.E. was supported by the EERE Solar Energy Technologies Office, DOE grant number DE-EE0009344. A.J. was supported by the NSF through the UD-CHARM University of Delaware MRSEC Center (no. DMR-2011824) and acknowledge the use of Bridges-2 at PSC through allocation DMR150099 from the Advanced Cyberinfrastructure Coordination Ecosystem: Services & Support (ACCESS) program and the DARWIN computing system at the University of Delaware, which is supported by the NSF grant number 1919839.

Publisher Copyright:
© 2023 American Chemical Society.


  • calcium stannate
  • chemical doping
  • density functional calculations
  • high-voltage electronics
  • hybrid molecular beam epitaxy (hMBE)
  • metal−semiconductor field-effect transistor (MESFET)
  • ultrawide band gap (UWBG) semiconductors

MRSEC Support

  • Shared

PubMed: MeSH publication types

  • Journal Article


Dive into the research topics of 'Doping the Undopable: Hybrid Molecular Beam Epitaxy Growth, n-Type Doping, and Field-Effect Transistor Using CaSnO3'. Together they form a unique fingerprint.

Cite this