Strain Relaxation via Phase Transformation in High-Mobility SrSnO 3 Films

Tristan K. Truttmann, Fengdeng Liu, Javier Garcia-barriocanal, Richard D. James, Bharat Jalan

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SrSnO3 (SSO) is an emerging ultrawide band gap (UWBG) semiconductor with potential in high-power applications. In-plane compressive strain was recently shown to stabilize the high-temperature tetragonal phase of SSO at room temperature (RT), which exists at T ≥ 1062 K in bulk. Here, we report on the study of strain relaxation in the epitaxial, tetragonal phase of Nd-doped SSO films grown on GdScO3 (110) (GSO) substrates and how it influences the electronic transport properties. The thinnest SSO film (thickness, t = 12 nm) yielded a fully coherent tetragonal phase at RT. At 12 nm < t < 110 nm, the tetragonal phase first transformed into the orthorhombic phase, and then at t ≥ 110 nm, the orthorhombic phase began to relax by forming misfit dislocations. Remarkably, the tetragonal phase remained fully coherent until it completely transformed into the orthorhombic phase. A significant increase in mobility from 14 to 73 cm2 V-1 s-1 was discovered between 12 and 330 nm. Using thickness- A nd temperature-dependent electronic transport measurements, we discuss the important roles of the surface, phase coexistence, and misfit dislocations on carrier density and mobility in Nd-doped SSO. This study provides unprecedented insight into the effect of thickness and strain relaxation behavior and their consequences for electronic transport in doped SSO with implications for high-power electronic devices.

Original languageEnglish (US)
Pages (from-to)1127-1132
Number of pages6
JournalACS Applied Electronic Materials
Issue number3
StatePublished - Mar 1 2021

Bibliographical note

Funding Information:
This work was supported by the Air Force Office of Scientific Research (AFOSR) through Grant no. FA9550-19-1-0245 and through NSF DMR-1741801. The work also benefitted from the Norwegian Centennial Chair Program (NOCC) and a Vannevar Bush Faculty Fellowship. Parts of this work were carried out at the Minnesota Nano Center and Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program under Award Number DMR-2011401.

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  • critical thickness
  • octahedral rotations
  • perovskite oxides
  • stannates
  • strain engineering
  • strain relaxation
  • ultrawide band gap semiconductors

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