Issue 2, 2016

Conductance and capacitance of bilayer protective oxides for silicon water splitting anodes

Abstract

State-of-the-art silicon water splitting photoelectrochemical cells employ oxide protection layers that exhibit electrical conductance in between that of dielectric insulators and electronic conductors, optimizing both built-in field and conductivity. The SiO2-like layer interposed between a deposited protective oxide film and its Si substrate plays a key role as a tunnel oxide that can dominate the total device impedance. In this report, we investigate the effects of changes in interfacial SiO2 resistance and capacitance in the oxide bilayer through both solid state leakage current and capacitance–voltage measurements and through electrochemical methods applied to water splitting cells. Modelling is performed to describe both types of data in a simple and intuitive way, allowing for insights to be developed into the connections among both the dielectric (charge storage) and conductive (charge transport) properties of bilayer protective oxides and their effects on oxygen evolution performance. Finally, atomic layer deposited (ALD) Al2O3 is studied as an insulator layer with conductivity intermediate between that of tunnel oxide SiO2 and the more conductive ALD-TiO2, to further generalize this understanding.

Graphical abstract: Conductance and capacitance of bilayer protective oxides for silicon water splitting anodes

Supplementary files

Article information

Article type
Paper
Submitted
12 Aug 2015
Accepted
09 Nov 2015
First published
19 Nov 2015

Energy Environ. Sci., 2016,9, 504-516

Author version available

Conductance and capacitance of bilayer protective oxides for silicon water splitting anodes

A. G. Scheuermann, K. W. Kemp, K. Tang, D. Q. Lu, P. F. Satterthwaite, T. Ito, C. E. D. Chidsey and P. C. McIntyre, Energy Environ. Sci., 2016, 9, 504 DOI: 10.1039/C5EE02484F

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