Microsecond Pulse I-V Approach to Understanding Defects in High Mobility Bi-layer Oxide Semiconductor Transistor

Area of Science:

• Materials Science
• Semiconductor Physics
• Device Engineering

Background:

• Amorphous oxide semiconductors (AOS) exhibit device instability due to defects and sub-gap states.
• Understanding charge trapping mechanisms is crucial for reliable AOS transistors in production.

Purpose of the Study:

• Investigate transient charging effects and charge trapping mechanisms in high-mobility bilayer oxide semiconductor transistors.
• Analyze dynamic charge transport to understand defect-related device instability.

Main Methods:

• Utilized microsecond ramps, pulse ID-VG, and transient/discharge current analysis.
• Examined high-mobility single HfInZnO (HIZO) and bilayer HfInZnO-InZnO (HIZO-IZO) transistors.

Main Results:

• Bilayer HIZO-IZO transistors showed a 28.8% mobility enhancement, significantly less than single HIZO (173.8%), in a charge-trapping-free environment.
• Transient charge trapping was categorized into temperature-insensitive fast charging and thermally activated slow charging with distinct trap energies.
• Low sub-gap state density in bilayer oxide TFTs explained the insignificant fast transient charging.

Conclusions:

• Defect characterization and transient charging analysis are vital for understanding and mitigating instability in oxide TFTs.
• The findings provide insights into optimizing AOS device performance and reliability for electronic applications.