TY - JOUR
T1 - Electrochemically driven degradation of chemical solution deposited ferroelectric thin-films in humid ambient
AU - Dahl-Hansen, Runar Plünnecke
AU - Polfus, Jonathan Marc
AU - Vøllestad, Einar
AU - Akkopru-Akgun, Betul
AU - Denis, Lyndsey
AU - Coleman, Kathleen
AU - Tyholdt, Frode
AU - Trolier-Mckinstry, Susan
AU - Tybell, Thomas
N1 - Funding Information:
This work was supported by the Research Council of Norway under the NBRIX-project (Project No. 247781/O30), the Center for Dielectric Studies, and the National Science Foundation (No. IIP-1841453). The author would like to give a special thanks to the Trolier-McKinstry group at the Penn State University for their valuable advice and assistance with this work. The author would also like to thank Paul Wittendorp and Lars-Geir Whist Tvedt for their assistance related to thin-film deposition and characterization.
Publisher Copyright:
© 2020 Author(s).
PY - 2020/6/28
Y1 - 2020/6/28
N2 - The ambient humidity significantly accelerates the degradation of lead zirconate titanate (PZT) films in microelectromechanical systems; the cause of such degradation is under debate. Here, it is shown that the degradation of chemical solution derived PZT thin-films in humid conditions is driven by the system's electrochemical activity toward water electrolysis. The layer stacks with Pt-based electrodes exhibited a faster degradation rate owing to their higher electrocatalytic activity compared to Au. A degradation model is proposed based on the electrolysis of liquid or gaseous H2O, involving the evolution of oxygen and hydrogen gas at the top and bottom electrodes. Degradation proceeds above the threshold voltage for a given electrode system and is driven by the evolution and pressure build-up of gaseous species at the PZT/electrode interfaces. The pressure build-up causes film cracking, delamination of the film and electrodes, electrothermal breakdown events, and eventually time-dependent dielectric breakdown. Significantly larger post-breakdown crater sizes in humid than in dry conditions suggests that larger cracks through which dielectric breakdown through humidified air can occur. Overall, these effects are shown to cause sample failure up to six orders of magnitude of time earlier than for operation in dry conditions. Thus, in order to improve the resilience of thin-film systems in humid conditions, it is imperative to protect the electrochemically active electrode components of the device.
AB - The ambient humidity significantly accelerates the degradation of lead zirconate titanate (PZT) films in microelectromechanical systems; the cause of such degradation is under debate. Here, it is shown that the degradation of chemical solution derived PZT thin-films in humid conditions is driven by the system's electrochemical activity toward water electrolysis. The layer stacks with Pt-based electrodes exhibited a faster degradation rate owing to their higher electrocatalytic activity compared to Au. A degradation model is proposed based on the electrolysis of liquid or gaseous H2O, involving the evolution of oxygen and hydrogen gas at the top and bottom electrodes. Degradation proceeds above the threshold voltage for a given electrode system and is driven by the evolution and pressure build-up of gaseous species at the PZT/electrode interfaces. The pressure build-up causes film cracking, delamination of the film and electrodes, electrothermal breakdown events, and eventually time-dependent dielectric breakdown. Significantly larger post-breakdown crater sizes in humid than in dry conditions suggests that larger cracks through which dielectric breakdown through humidified air can occur. Overall, these effects are shown to cause sample failure up to six orders of magnitude of time earlier than for operation in dry conditions. Thus, in order to improve the resilience of thin-film systems in humid conditions, it is imperative to protect the electrochemically active electrode components of the device.
UR - http://www.scopus.com/inward/record.url?scp=85087548929&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85087548929&partnerID=8YFLogxK
U2 - 10.1063/5.0003989
DO - 10.1063/5.0003989
M3 - Article
AN - SCOPUS:85087548929
SN - 0021-8979
VL - 127
JO - Journal of Applied Physics
JF - Journal of Applied Physics
IS - 24
M1 - 244101
ER -