Ultrathin α-Bi₂O₃ Thin-Film Transistor for Cost-Effective Oxide-TFT Inverters

Area of Science:

• Materials Science
• Electronics Engineering
• Semiconductor Physics

Background:

• Advancements in electronics prioritize energy efficiency and sustainability.
• Metal oxide thin-film transistors (TFTs) are key to next-generation sustainable electronics.
• Exploring novel oxide channel compositions is crucial for device innovation.

Purpose of the Study:

• To develop n-channel alpha-Bi2O3 TFTs using a cost-effective fabrication method.
• To investigate the effect of oxygen-containing post-annealing on device performance.
• To demonstrate the feasibility of alpha-Bi2O3 TFTs in circuit applications.

Main Methods:

• Fabrication of 4 nm ultrathin alpha-Bi2O3 channels via vacuum-free, solvent-free liquid metal printing in ambient air.
• Characterization of pristine and post-annealed devices to analyze electrical properties.
• Fabrication and testing of zero-VGS-NMOS and CMOS inverter circuits using alpha-Bi2O3 TFTs.

Main Results:

• Pristine devices showed TFT action but required large negative gate bias due to oxygen vacancies.
• Oxygen-containing post-annealing reduced carrier density and subgap defects.
• Developed depletion and enhancement-type alpha-Bi2O3 TFTs with saturation mobility of 2-4 cm^2 V^-1 s^-1.
• Fabricated inverter circuits achieved a high voltage gain exceeding 130.

Conclusions:

• Ultrathin alpha-Bi2O3 TFTs can be fabricated cost-effectively using liquid metal printing.
• Post-annealing is effective in optimizing the performance of alpha-Bi2O3 TFTs.
• Alpha-Bi2O3 TFTs show potential for next-generation sustainable electronics and integrated circuits.