Open AccessElectrochemical Stability of n-Si Photoanodes Protected by TiO2 Thin Layers Grown by Atomic Layer Deposition
Author(s) -
Maxime E. Dufond,
J.N. Chazalviel,
Lionel Santinacci
Publication year - 2021
Publication title -
journal of the electrochemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.258
H-Index - 271
eISSN - 1945-7111
pISSN - 0013-4651
DOI - 10.1149/1945-7111/abeaf3
Subject(s) - atomic layer deposition , photocurrent , materials science , titanium , electrochemistry , corrosion , layer (electronics) , electrode , chemical engineering , deposition (geology) , open circuit voltage , analytical chemistry (journal) , thin film , nanotechnology , chemistry , metallurgy , optoelectronics , paleontology , sediment , chromatography , engineering , biology , physics , voltage , quantum mechanics
This work investigates the n-Si photoanodes corrosion protection by Atomic Layer Deposition (ALD) of a TiO 2 film. A specific electrochemical experimental sequence (including successive rest potential measurements and voltammetries under illumination or not) has been established to study the stability of the electrodes in KOH. Depending on the deposition conditions (precursor composition and temperature), the electrochemical properties of the layers are different. The photoanodes coated using titanium tetraisopropoxide (TTIP) at low temperature exhibit a low photocurrent ( j ph ) that is progressively enhanced during the electrochemical sequence and their stability decreases. When using tetrakis(dimethylamido)titanium (TDMAT), the j ph is almost constant and the film prevents from corrosion. The characterizations show that the ALD parameters drive the microstructure of the layer that is found critical for the electrochemical response. A hydrogen doping occurring during the open circuit potential measurements under illumination is evidenced by IR spectroscopy. It is mainly localized at the grain boundaries and pores of the layers as well as in the n-Si and it modifies the charge transfer at the electrode/solution junction and the hydrogen diffusion weakens the film causing the Si corrosion. The different charge transfer mechanisms are finally proposed depending on the ALD conditions and the film thickness.