Record mobility in transparent p-type tin monoxide films and devices by phase engineering

Area of Science:

• Materials Science
• Electronics Engineering
• Nanotechnology

Background:

• Transparent conductive oxides (TCOs) are crucial for electronic devices.
• Developing high-performance p-type TCOs processed at low temperatures remains a challenge.
• Existing p-type oxides often suffer from low mobility and stability issues.

Purpose of the Study:

• To fabricate fully transparent, nanoscale p-type tin oxide (SnO) thin film transistors (TFTs) at low processing temperatures (180 °C).
• To achieve record device performance, specifically high hole mobility.
• To investigate the role of phase engineering in enhancing the electrical properties of SnO thin films.

Main Methods:

• Physical vapor deposition (PVD) was used to deposit nanoscale SnO thin films.
• Precise control over process conditions was employed to engineer the film's phase composition.
• Fabrication of TFT devices on both rigid and flexible transparent substrates.
• Characterization of film properties including Hall mobility and device performance metrics.

Main Results:

• Achieved record Hall mobility of 18.71 cm(2) V(-1) s(-1) for SnO thin films.
• Fabricated TFTs exhibited linear field-effect mobility of 6.75 cm(2) V(-1) s(-1) on rigid substrates and 5.87 cm(2) V(-1) s(-1) on flexible substrates.
• Demonstrated that controlled amounts of residual metallic tin, not phase-pure SnO, significantly enhance hole mobility.
• Constructed a detailed phase stability map for PVD of nanoscale SnO.

Conclusions:

• Successfully fabricated high-performance, transparent, nanoscale p-type SnO TFTs at a low temperature of 180 °C.
• Phase engineering, specifically the controlled inclusion of metallic tin, is key to achieving high hole mobility in SnO.
• The developed fabrication process and phase map provide a pathway for advanced transparent electronics on various substrates.