High-Performance Tin Oxide Thin-Film Transistors Realized by Codoping and Their Application in Logic Circuits

Area of Science:

• Materials Science
• Semiconductor Physics
• Nanotechnology

Background:

• Tin oxide (SnO2) is a low-cost, eco-friendly semiconductor with a wide band gap, suitable for channel materials.
• Bulk SnO2 exhibits high electron mobility, but SnO2 thin-film transistors (TFTs) show moderate performance, limiting applications.
• Existing SnO2 TFTs face challenges in achieving both high electrical performance and operational stability.

Purpose of the Study:

• To enhance the electrical properties and stability of SnO2 TFTs through a codoping strategy.
• To investigate the impact of codoping content on the performance of SnO2 TFTs.
• To demonstrate the potential of codoped SnO2 TFTs in practical electronic circuits.

Main Methods:

• A codoping strategy using indium (In) and gallium (Ga) was employed to modify the SnO2 lattice.
• Comparative analysis of doped and undoped SnO2 thin films and their corresponding TFTs.
• Investigation of the effect of varying codopant concentrations on device characteristics.

Main Results:

• Codoping effectively reduced impurity-induced strain by leveraging differences in ionic radii.
• Optimal codoped SnO2 (TIGO) TFTs achieved a field-effect mobility of 15.9 cm²/V·s, a threshold voltage of 0.2 V, and an on-to-off current ratio of 2.2 × 10⁷.
• The TIGO TFTs exhibited excellent stability under bias stress, with small threshold voltage shifts, and were used to build a high-gain (10.76) unipolar inverter.

Conclusions:

• Codoping SnO2 with In and Ga is an effective strategy to overcome the performance limitations of SnO2 TFTs.
• The optimized TIGO TFTs demonstrate superior electrical performance and stability, suitable for advanced electronic applications.
• This study validates the potential of codoped SnO2 for next-generation electronic devices.