Composition, Microstructure, and Electrical Performance of Sputtered SnO Thin Films for p-Type Oxide Semiconductor

Area of Science:

• Materials Science
• Solid State Physics
• Thin Film Technology

Background:

• Tin oxide (SnO) is a promising material for electronic applications.
• Controlling the Sn/O ratio is crucial for achieving desired semiconductor properties.
• Existing deposition methods often struggle with precise stoichiometry control.

Purpose of the Study:

• To investigate the effect of Sn/O ratio on the properties of SnO thin films.
• To develop a method for producing p-type SnO thin films with tunable electrical characteristics.
• To understand the relationship between composition, structure, and electrical properties.

Main Methods:

• Cosputtering of ceramic SnO and metal Sn targets at room temperature.
• Varying DC sputtering power on the Sn target to control the Sn/O ratio.
• Microwave-assisted thermal annealing in air.
• Characterization using Hall effect measurements and stress analysis.

Main Results:

• Tetragonal SnO crystallization achieved with specific Sn/O ratios after annealing.
• Films exhibited p-type semiconductor behavior below a Sn/O ratio of 55:45, and metallic behavior above.
• Highest Hall mobility (8.8 cm²/V·s) and hole concentration (5.4 × 10¹⁸ cm⁻³) observed at a Sn/O ratio of 55:45.
• Trap-mediated hopping observed in cosputtered films, contrasting with band conduction in pure SnO.

Conclusions:

• The Sn/O ratio is a critical parameter for controlling the electrical properties of SnO thin films.
• Cosputtering and annealing offer a viable route to synthesize high-performance p-type SnO semiconductors.
• Residual stress plays a significant role in the observed property variations.