Titanium Oxide Crystallization and Interface Defect Passivation for High Performance Insulator-Protected Schottky...

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Atomic layer deposited (ALD) TiO2 protection layers are crucial for developing efficient and stable photoanodes for solar fuel synthesis.
• However, understanding the mechanisms controlling conductivity and photovoltage in TiO2-protected silicon anodes remains a challenge.

Purpose of the Study:

• To investigate the impact of hydrogen-containing annealing treatments on TiO2-protected silicon anodes.
• To elucidate the mechanisms responsible for improved photovoltage and stability in these photoanodes.

Main Methods:

• Utilizing atomic layer deposition (ALD) to create TiO2 protection layers on silicon anodes.
• Implementing post-catalyst deposition annealing treatments at intermediate temperatures in hydrogen-containing atmospheres.
• Characterizing the oxide/silicon interface, TiO2 crystallization, and dielectric properties.

Main Results:

• Intermediate temperature annealing reproducibly decreases oxide/silicon interface trap densities.
• This annealing process leads to a significant increase in photovoltage, suppressing previously observed insulator thickness-dependent losses.
• TiO2 crystallization and increased dielectric constant were observed concurrently with improved performance.
• A record photovoltage of 623 mV for a Schottky junction photoanode was achieved.

Conclusions:

• Hydrogen-containing annealing treatments are effective in optimizing TiO2-protected silicon anodes for solar fuel production.
• The reduction in interface traps and enhanced TiO2 properties are key to achieving high photovoltage and stability.
• These findings pave the way for more efficient solar fuel synthesis using advanced photoanode designs.