Field Dependent Electrical Conduction in Metal-Insulator-Metal Devices using Alumina-Silicone Nanolaminate Dielectrics
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Field Dependent Electrical Conduction in Metal-Insulator-Metal Devices using AluminaSilicone Nanolaminate Dielectrics Santosh K. Sahoo,1,2 Rakhi P. Patel,3 and Colin A. Wolden3 1
National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401, USA
2
New Jersey Institute of Technology, Newark, New Jersey 07102, USA
3
Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado 80401, USA ABSTRACT Hybrid alumina-silicone nanolaminate films were synthesized by plasma enhanced chemical vapor deposition (PECVD) process. PECVD allows digital control over nanolaminate construction, and may be performed at low temperature for compatibility with flexible substrates. These materials are being considered as dielectrics for application such as capacitors in thin film transistors and memory devices. In this work, we present the temperature dependent current versus voltage (I-V) measurements of the nanolaminate dielectrics in the range of 200- 310 K to better asses their potential in these applications. Various models are used to know the different conduction mechanisms contributing to the leakage current in these nanolaminate films. It is observed that space charge limited current (SCLC) mechanism is the dominant conduction process in the high field region whereas Ohmic conduction process is contributing to the leakage current in the low field region. The shallow electron trap level energy (Et) of 0.16 eV is responsible for SCLC mechanism whereas for Ohmic conduction process the activation energy (Ea) for electrons is about 0.22 eV. An energy band diagram is given to explain the dominance of various conduction mechanisms in different field regions in these nanolaminate films. INTRODUCTION Hybrid nanolaminates comprised of polymer and inorganic layers are being pursued to serve a number of roles to enable flexible opto-electronics [1-3]. Thin film transistors (TFTs) are an important component in low cost, large area electronics such as flat panel displays and smart cards. The quality of the dielectric layer can significantly impact TFT performance, particularly when using organic semiconductors [4-6]. Ideally these materials provide a high specific capacitance to reduce turn-on voltage requirements (< 5 V), as well as low leakage to maintain a high on/off current ratios (>105). These demands have been met by inorganic nanolaminates, [79] but the use of these structures is limited in applications requiring flexibility. Multi-layer structures consisting of alternating inorganic and organic layers have been demonstrated to be effective dielectrics for devices fabricated on flexible substrates [1]. Various inorganic/organic hybrid dielectrics are explored to date and numerous material combinations have been explored [4-6,10-12]. Popular polymers include poly (4-vinylphenol) (PVP) and poly (methyl methacrylate) (PMMA). The inorganic material is typically a high dielectric constant (high-k) metal oxide (e. g. TiO2, Ta2O5, Al2O3, HfO2, YOx). The different geometries studied so far incl
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