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Electrical, Photoelectrochemical, and Photoelectron Spectroscopic Investigation of the Interfacial Transport and Energetics of Amorphous TiO2/Si Heterojunctions
journal contribution
posted on 2015-12-15, 00:00 authored by Shu Hu, Matthias H. Richter, Michael F. Lichterman, Joseph Beardslee, Thomas Mayer, Bruce S. Brunschwig, Nathan S. LewisSolid-state electrical, photoelectrochemical,
and photoelectron
spectroscopic techniques have been used to characterize the behavior
and electronic structure of interfaces between n-Si, n+-Si, or p+-Si surfaces and amorphous coatings of TiO2 formed using atomic-layer deposition. Photoelectrochemical
measurements of n-Si/TiO2/Ni interfaces in contact with
a series of one-electron, electrochemically reversible redox systems
indicated that the n-Si/TiO2/Ni structure acted as a buried
junction whose photovoltage was independent of the formal potential
of the contacting electrolyte. Solid-state current–voltage
analysis indicated that the built-in voltage of the n-Si/TiO2 heterojunction was ∼0.7 V, with an effective Richardson constant
∼1/100th of the value of typical Si/metal Schottky barriers.
X-ray photoelectron spectroscopic data allowed formulation of energy
band-diagrams for the n-Si/TiO2, n+-Si/TiO2, and p+-Si/TiO2 interfaces. The XPS
data were consistent with the rectifying behavior observed for amorphous
TiO2 interfaces with n-Si and n+-Si surfaces
and with an ohmic contact at the interface between amorphous TiO2 and p+-Si.