Titanium Oxide Crystallization and Interface Defect Passivation for High Performance Insulator-Protected Schottky Junction MIS Photoanodes

• DOI: 10.1021/acsami.6b03688
• Publication Date: 2016-05-20T02:27:17Z
• Authors: Andrew G. Scheuer...; John P. Lawrence; Andrew C. Meng; Kechao Tang; Olivia L. Hendricks; Christopher E. D....; Paul C. McIntyre
• Keywords: 02 engineering and technology; 0210 nano-technology; 01 natural sciences; 7. Clean energy; 0104 chemical sciences

Atomic layer deposited (ALD) TiO2 protection layers may allow for the development of both highly efficient and stable photoanodes for solar fuel synthesis; however, the very different conductivities and photovoltages reported for TiO2-protected silicon anodes prepared using similar ALD conditions indicate that mechanisms that set these key properties are, as yet, poorly understood. In this report, we study hydrogen-containing annealing treatments and find that postcatalyst-deposition anneals at intermediate temperatures reproducibly yield decreased oxide/silicon interface trap densities and high photovoltage. A previously reported insulator thickness-dependent photovoltage loss in metal-insulator-semiconductor Schottky junction photoanodes is suppressed. This occurs simultaneously with TiO2 crystallization and an increase in its dielectric constant. At small insulator thickness, a record for a Schottky junction photoanode of 623 mV photovoltage is achieved, yielding a photocurrent turn-on at 0.92 V vs NHE or -0.303 V with respect to the thermodynamic potential for water oxidation.