Multifunctional Oxygen Scavenger Layer for High-Performance Oxide Thin-Film Transistors with Low-Temperature...

Area of Science:

• Materials Science
• Electronics Engineering
• Semiconductor Physics

Background:

• Amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) are crucial for flexible electronics.
• Improving the electrical characteristics and operational stability of a-IGZO TFTs remains a key challenge.
• Low-temperature fabrication processes are essential for cost-effective manufacturing and substrate compatibility.

Purpose of the Study:

• To introduce an oxygen scavenger layer (OSL) as a back channel in a-IGZO TFTs.
• To enhance the electrical properties and stability of a-IGZO TFTs.
• To enable low-temperature fabrication of high-performance a-IGZO TFTs.

Main Methods:

• Fabrication of a-IGZO TFTs with and without an OSL.
• The OSL was a hafnium (Hf)-doped a-IGZO channel layer deposited via radio-frequency magnetron cosputtering.
• Electrical characterization and positive bias temperature stress (PBTS) testing were performed on the fabricated TFTs.

Main Results:

• a-IGZO TFTs with OSL exhibited superior electrical characteristics, including higher field-effect mobility (31.08 vs 9.25 cm²/V s) and on/off current ratio (1.73 × 10¹⁰ vs 8.68 × 10⁸).
• The subthreshold swing improved from 0.43 to 0.32 V/decade with the OSL.
• Stability under PBTS was significantly enhanced, with a reduced threshold voltage shift (2.31 vs 9.22 V) after stress at 50 °C for 10,000 s.
• These improvements were achieved with annealing at a low temperature of 200 °C.

Conclusions:

• The incorporation of an Hf-doped OSL as a back channel effectively enhances the electrical performance and stability of a-IGZO TFTs.
• The OSL functions by absorbing oxygen ions, thereby improving the front channel quality near the interface.
• This approach enables low-temperature fabrication of high-performance and stable a-IGZO TFTs, suitable for various electronic applications.