Engineering SrSnO₃ Phases and Electron Mobility at Room Temperature Using Epitaxial Strain

Area of Science:

• Materials Science
• Solid State Physics
• Condensed Matter Physics

Background:

• High-speed electronics demand epitaxial films with superior room-temperature (RT) carrier mobility.
• Alkaline-earth stannates offer potential for ambient-temperature oxide electronics due to high RT mobility.
• Previous stannate film mobility was hindered by dislocations, preventing fully coherent film growth.

Purpose of the Study:

• To demonstrate the growth of coherent, strain-engineered epitaxial strontium stannate (SrSnO3) films.
• To investigate the effect of compressive strain on the crystal and electronic structures of SrSnO3 films.
• To achieve enhanced carrier mobility in SrSnO3 films for advanced oxide electronics.

Main Methods:

• Radical-based molecular beam epitaxy for growing epitaxial SrSnO3 films.
• Application of compressive strain to stabilize specific crystalline phases at RT.
• Temperature-dependent synchrotron-based X-ray measurements.
• Electronic transport measurements.
• First-principles calculations.

Main Results:

• Successfully grew coherent, strain-engineered SrSnO3 films.
• Compressive strain stabilized the high-symmetry tetragonal phase of SrSnO3 at RT.
• Achieved over 300% mobility enhancement in doped films compared to the orthorhombic polymorph.
• Detailed understanding of strain-dependent crystal and electronic structures.

Conclusions:

• Strain engineering is crucial for overcoming limitations in stannate film growth and mobility.
• Stabilizing the tetragonal phase via compressive strain significantly boosts RT carrier mobility.
• Strain-engineered stannate films are promising for high-mobility, optically transparent oxide electronics operating at RT.