Correlation Between Currents, X-ray Diffraction Patterns and Transfer Characteristics of SnO₂ Thin Film Transistor

Area of Science:

• Materials Science
• Electronics Engineering
• Semiconductor Physics

Background:

• Tin oxide (SnO₂) is a promising n-type semiconductor for thin film transistors (TFTs).
• Gate insulator properties significantly influence TFT performance.
• Understanding the correlation between material structure and device characteristics is crucial for optimizing TFTs.

Purpose of the Study:

• To investigate the impact of SnO₂ crystallinity and bonding structure on TFT performance.
• To explore the role of oxygen vacancies and Schottky barriers in amorphous SnO₂ TFTs.
• To compare the transfer characteristics of crystalline and amorphous SnO₂/SiOC TFTs.

Main Methods:

• Fabrication of SnO₂ thin film transistors (TFTs) with SiOC gate insulators on n-type Si substrates.
• Annealing processes to control SnO₂ crystallinity.
• Analysis of SnO₂ bonding structures and oxygen vacancy concentrations.
• Electrical characterization of TFTs, including transfer characteristics and mobility measurements.

Main Results:

• SnO₂ current increased with enhanced crystallinity, which was achieved through annealing.
• High oxygen flow during deposition led to amorphous SnO₂ structures after annealing, with decreased current but high oxygen vacancies.
• Amorphous SnO₂/SiOC TFTs demonstrated higher stability-mobility than crystalline counterparts due to increased diffusion current at the depletion layer and high Schottky barriers.

Conclusions:

• Annealing is effective in increasing SnO₂ crystallinity, thereby enhancing current.
• Amorphous SnO₂ structures, despite lower crystallinity, can yield TFTs with superior ambipolar transfer characteristics and stability-mobility.
• The interplay between amorphous structure, oxygen vacancies, and Schottky barriers is key to achieving high-performance SnO₂ TFTs.