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Large-area ultrathin Te films with substrate-tunable orientation
Elisabeth Bianco1, Rahul Rao, Michael Snure
1Department of Chemistry, Rice University, 6100 Main Street, Houston, TX 77005, USA.
Nanoscale
|June 9, 2020
Summary
Researchers developed a new sputtering method to grow ultrathin tellurium (Te) films with controlled crystal orientation. This technique allows for tunable electronic and optical properties in 2D materials for advanced devices.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Material anisotropy leads to property variations based on crystal orientation.
- Controlling material orientation is key to tuning mechanical, optical, and electronic properties.
- Two-dimensional (2D) materials offer unique properties due to their reduced dimensionality.
Purpose of the Study:
- To develop a novel sputtering approach for growing ultrathin tellurium (Te) films with controlled crystalline orientation.
- To investigate the orientation-dependent properties of these Te films.
- To explore the potential applications of these films in electronic and optoelectronic devices.
Main Methods:
- Utilized a novel sputtering technique to grow ultrathin Te films (2.5-10 nm).
- Employed polarized Raman spectroscopy and high-resolution electron microscopy to characterize film orientation.
- Performed Hall effect measurements to determine carrier mobility.
- Investigated film texture and growth on different substrates like highly oriented pyrolytic graphite (HOPG) and MgO(100).
Main Results:
- Achieved rational control of crystalline orientation, with Te 〈0001〉 helical chains aligning parallel to HOPG and perpendicular to MgO(100) substrates.
- Observed textured growth on HOPG, differing from previous reports.
- Grew large-area (>1 cm²) ultrathin Te films at low temperatures (25 °C), compatible with flexible substrates.
- Demonstrated orientation-dependent carrier mobility up to 19 cm²/V·s.
- Found that optical anisotropy persists and is enhanced at the ultrathin limit, with thickness-dependent Raman signals.
Conclusions:
- The novel sputtering method enables scalable production of large-area, ultrathin Te films with controlled orientation.
- These films exhibit significant orientation-dependent electronic properties, particularly carrier mobility.
- The ability to control orientation opens new possibilities for designing semiconducting thin films with tailored properties for electronic and optoelectronic applications.
