Defect Chemistry Engineered SnO₂ Thin Films via Thermal ALD: Unraveling Defect-Controlled Electronic Structure for...

Area of Science:

• Materials Science
• Surface Science
• Solid State Physics

Background:

• Atomic layer deposition (ALD) enables precise thin film fabrication.
• Tin dioxide (SnO₂) is a promising semiconductor for various electronic applications.
• Understanding defect chemistry is crucial for tuning SnO₂ electronic properties.

Purpose of the Study:

• To investigate the influence of growth temperature on SnO₂ thin films fabricated by ALD.
• To elucidate the relationship between defect chemistry, electronic structure, and film properties.
• To identify optimal ALD conditions for specific applications.

Main Methods:

• Fabrication of SnO₂ thin films using ALD with tetrakis(dimethylamino)tin (TDMASn) and H₂O from 50-200 °C.
• Characterization using photoelectron spectroscopy (UPS, LEIPS), ion beam analysis (IBA), deuterium labeling, ERDA, and HER measurements.
• Electrical transport analysis to assess conductivity and defect impacts.

Main Results:

• Film properties vary significantly with deposition temperature (50-200 °C).
• Low temperatures (50-100 °C) yield oxygen-rich films with organic residues and hydrogen, creating midgap states that enhance surface emission but impede bulk transport.
• Higher temperatures (150-200 °C) improve crystallinity and reduce impurities; 150 °C offers an optimal balance with high work function and electron affinity, driven by hydrogen-related traps.
• 200 °C results in oxygen vacancies and Sn²⁺ states, lowering injection barriers but reducing surface conductivity.

Conclusions:

• Defect-induced electronic restructuring profoundly influences SnO₂ properties beyond bandgap.
• ALD growth temperature is a key parameter for controlling defect chemistry and electronic properties.
• ALD-grown SnO₂ can be tuned for applications like electron transport layers, catalysts, and transparent conductors by optimizing synthesis strategies.