Analysis of Nanoporosity in Moisture Permeation Barrier Layers by Electrochemical Impedance Spectroscopy.

Water permeation in inorganic moisture permeation barriers occurs through macroscale defects/pinholes and nanopores, the latter with size approaching the water kinetic diameter (0.27 nm). Both permeation paths can be identified by the calcium test, i.e., a time-consuming and expensive optical method for determining the water vapor transmission rate (WVTR) through barrier layers. Recently, we have shown that ellipsometric porosimetry (i.e., a combination of spectroscopic ellipsometry and isothermal adsorption studies) is a valid method to classify and quantify the nanoporosity and correlate it with the WVTR values. Nevertheless, no information is obtained about the macroscale defects or the kinetics of water permeation through the barrier, both essential in assessing the quality of the barrier layer. In this study, electrochemical impedance spectroscopy (EIS) is shown as a sensitive and versatile method to obtain information on nanoporosity and macroscale defects, water permeation, and diffusivity of moisture barrier layers, complementing the barrier property characterization obtained by means of EP and calcium test. EIS is performed on thin SiO2 barrier layers deposited by plasma enhanced-CVD. It allows the determination of the relative water uptake in the SiO2 layers, found to be in agreement with the nanoporosity content inferred by EP. Furthermore, the kinetics of water permeation is followed by EIS, and the diffusivity (D) is determined and found to be in accordance with literature values. Moreover, differently from EP, EIS data are shown to be sensitive to the presence of local macrodefects, correlated with the barrier failure during the calcium test.

[1]  Piet C.P. Bouten,et al.  P‐88: Thin Film Encapsulation for OLEDs: Evaluation of Multi‐layer Barriers using the Ca Test , 2003 .

[2]  D. Landolt,et al.  Electrochemical Determination of the Porosity of Single and Duplex PVD Coatings of Titanium and Titanium Nitride on Brass , 1998 .

[3]  V. Barranco,et al.  Correlation of morphology and barrier properties of thin microwave plasma polymer films on metal substrate , 2004 .

[4]  Sung Min Cho,et al.  Water permeation through organic–inorganic multilayer thin films , 2012 .

[5]  C. Detavernier,et al.  Spacious and mechanically flexible mesoporous silica thin film composed of an open network of interlinked nanoslabs , 2011 .

[6]  Krishna Kant,et al.  The Influence of Nanopore Dimensions on the Electrochemical Properties of Nanopore Arrays Studied by Impedance Spectroscopy , 2014, Sensors.

[7]  John Lewis.  Material challenge for flexible organic devices , 2006 .

[8]  X. Nóvoa,et al.  Characterisation of the barrier properties of different paint systems: Part I. Experimental set-up and ideal Fickian diffusion , 1999 .

[9]  Mohamed Latreche,et al.  Defect-permeation correlation for ultrathin transparent barrier coatings on polymers , 2000 .

[10]  S. J. Gregg,et al.  Adsorption Surface Area and Porosity , 1967 .

[11]  H. Lifka,et al.  Cathode encapsulation of organic light emitting diodes by atomic layer deposited Al2O3 films and Al2O3/a-SiNx:H stacks , 2012 .

[12]  Yong Jin Jeong,et al.  Al2O3/TiO2 nanolaminate thin film encapsulation for organic thin film transistors via plasma-enhanced atomic layer deposition. , 2014, ACS applied materials & interfaces.

[13]  Zhe-sheng Feng,et al.  A novel humidity sensor based on alumina nanowire films , 2012 .

[14]  Z. Hens,et al.  Electrochemical impedance spectroscopy at semiconductor electrodes: the recombination resistance revisited , 1997 .

[15]  Lorenzo Fedrizzi,et al.  Organic coating capacitance measurement by EIS: ideal and actual trends , 1999 .

[16]  Antoine Goullet,et al.  Optical spectroscopic analyses of OH incorporation into SiO2 films deposited from O2/tetraethoxysilane plasmas , 2000 .

[17]  C. Sanchez,et al.  Porosity and mechanical properties of mesoporous thin films assessed by environmental ellipsometric porosimetry. , 2005, Langmuir : the ACS journal of surfaces and colloids.

[18]  Florian Mansfeld,et al.  Use of electrochemical impedance spectroscopy for the study of corrosion protection by polymer coatings , 1995 .

[19]  P. T. Lai,et al.  TECHNICAL NOTE: Moisture sensitive field effect transistors using ? gate structure , 1999 .

[20]  M. R. Baklanov,et al.  Determination of pore size distribution in thin films by ellipsometric porosimetry , 2000 .

[21]  D. Vanmaekelbergh,et al.  Impedance spectroscopy at semiconductor electrodes: Review and recent developments , 1996 .

[22]  H. Yasuda,et al.  Spectroscopic and electrochemical characterisation of thin cathodic plasma polymer films on iron , 2004 .

[23]  Devanshi.  Characterisation of BE , 2008 .

[24]  R. Schropp,et al.  Using hot wire and initiated chemical vapor deposition for gas barrier thin film encapsulation , 2015 .

[25]  Silvia Colodrero,et al.  Sorption Properties of Mesoporous Multilayer Thin Films , 2008 .

[26]  Anthony P. Roberts,et al.  Gas permeation in silicon-oxide/polymer (SiOx/PET) barrier films: role of the oxide lattice, nano-defects and macro-defects , 2002 .

[27]  M. Ritala,et al.  Corrosion Protection of Steel with Oxide Nanolaminates Grown by Atomic Layer Deposition , 2011 .

[28]  Mohd Nizar Hamidon,et al.  Humidity Sensors Principle, Mechanism, and Fabrication Technologies: A Comprehensive Review , 2014, Sensors.

[29]  S. George,et al.  Oxidation Kinetics of Calcium Films by Water Vapor and Their Effect on Water Vapor Transmission Rate Measurements , 2014 .

[30]  D. M. Brasher,et al.  Electrical measurements in the study of immersed paint coatings on metal. I. Comparison between capacitance and gravimetric methods of estimating water-uptake , 2007 .

[31]  M. Sanden,et al.  Evidence of the filling of nano-porosity in SiO2-like layers by an initiated-CVD monomer , 2012 .

[32]  G. Grundmeier,et al.  Combined EIS and FTIR-ATR study of water uptake and diffusion in polymer films on semiconducting electrodes , 2007 .

[33]  F. Mansfeld,et al.  Analysis of EIS Data for Common Corrosion Processes , 1993 .

[34]  Paul E. Burrows,et al.  Mechanisms of Vapor Permeation Through Multilayer Barrier Films: Lag Time Versus Equilibrium Permeation , 2004 .

[35]  S. Kordic,et al.  Electrochemical impedance spectroscopy of dense silica and porous silicon oxycarbide , 2007 .

[36]  C. Sanchez,et al.  Determination of pore size distribution in thin organized mesoporous silica films by spectroscopic ellipsometry in the visible and infrared range , 2003 .

[37]  R. Spontak,et al.  Morphology and gas barrier properties of thin SiO_xcoatings on polycarbonate: Correlations with plasma-enhanced chemical vapor deposition conditions , 2000 .

[38]  Steven M. George,et al.  Ca test of Al2O3 gas diffusion barriers grown by atomic layer deposition on polymers , 2006 .

[39]  K. Sing.  Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (Recommendations 1984) , 1985 .

[40]  Mikko Ritala,et al.  Electrochemical and time-of-flight secondary ion mass spectrometry analysis of ultra-thin metal oxide (Al2O3 and Ta2O5) coatings deposited by atomic layer deposition on stainless steel , 2011 .

[41]  M. Sanden,et al.  Initiated-chemical vapor deposition of organosilicon layers: Monomer adsorption, bulk growth, and process window definition , 2012 .

[42]  X. Nóvoa,et al.  Characterisation of the barrier properties of different paint systems. Part II. Non-ideal diffusion and water uptake kinetics , 1999 .

[43]  P. Taberna,et al.  Relation between the ion size and pore size for an electric double-layer capacitor. , 2008, Journal of the American Chemical Society.

[44]  A. Hughes,et al.  Unravelling the corrosion inhibition mechanisms of bi-functional inhibitors by EIS and SEM–EDS , 2013 .

[45]  K. Sing,et al.  Adsorption by Powders and Porous Solids: Principles, Methodology and Applications , 1998 .

[46]  T. Baumann,et al.  Unraveling the potential and pore-size dependent capacitance of slit-shaped graphitic carbon pores in aqueous electrolytes. , 2013, Physical chemistry chemical physics : PCCP.

[47]  Jorge Andrés Calderón Gutiérrez,et al.  Barrier property determination and lifetime prediction by electrochemical impedance spectroscopy of a high performance organic coating , 2014 .

[48]  N. Harvey,et al.  Activated Rate Theory Treatment of Oxygen and Water Transport through Silicon Oxide/Poly(ethylene terephthalate) Composite Barrier Structures , 1997 .

[49]  Atomic layer deposition-based tuning of the pore size in mesoporous thin films studied by in situ grazing incidence small angle X-ray scattering. , 2014, Nanoscale.

[50]  Nicolas Schiller,et al.  Permeation barrier properties of thin oxide films on flexible polymer substrates , 2009 .

[51]  A. Grill,et al.  Porosity in plasma enhanced chemical vapor deposited SiCOH dielectrics: A comparative study , 2003 .

[52]  J. G. Kim,et al.  A study on the quantitative determination of through-coating porosity in PVD-grown coatings , 2004 .

[53]  J. Wit,et al.  The determination of coating performance with impedance measurements—II. Water uptake of coatings , 1994 .

[54]  Yongjin Kim,et al.  The development of thin film barriers for encapsulating organic electronics , 2011, 2011 IEEE 61st Electronic Components and Technology Conference (ECTC).

[55]  P. Faia,et al.  AC impedance spectroscopy: a new equivalent circuit for titania thick film humidity sensors , 2005 .

[56]  Jorge Andrés Calderón-Gutierrez,et al.  BARRIER PROPERTY DETERMINATION AND LIFETIME PREDICTION BY ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY OF A HIGH PERFORMANCE ORGANIC COATING DETERMINACIÓN DE PROPIEDADES BARRERA Y DE PREDICCIÓN DE TIEMPO DE VIDA POR ESPECTROSCOPÍA DE IMPEDANCIA ELECTROQUÍMICA DE UN RECUBRIMIENTO ORGÁNICO DE ALTO RENDIMIEN , 2014 .

[57]  M. Matheron,et al.  Adsorption and Desorption Isotherms at Ambient Temperature Obtained by Ellipsometric Porosimetry to Probe Micropores in Ordered Mesoporous Silica Films , 2005 .

[58]  M. Ritala,et al.  Low-temperature atomic layer deposition of Al2O3 thin coatings for corrosion protection of steel: Surface and electrochemical analysis , 2011 .

[59]  A. Amirudin,et al.  Application of electrochemical impedance spectroscopy to study the degradation of polymer-coated metals , 1995 .

[60]  M. Donohue,et al.  Diffusion in fluids with large mean free paths: Non-classical behavior between Knudsen and Fickian limits , 2009 .

[61]  H. Abbasian,et al.  Capacitive humidity sensors based on large diameter porous alumina prepared by high current anodization , 2012 .

[62]  H. Amenitsch,et al.  Detailed study of the pore-filling processes during nanocasting of mesoporous films using SnO2/SiO2 as a model system , 2009 .

[63]  M. Sanden,et al.  On the role of nanoporosity in controlling the performance of moisture permeation barrier layers , 2014 .