Laser processing and chemistry: recent developments

The dielectric strength of a promising interlevel low relative permittivity dielectric is investigated for various film thicknesses and temperatures by using I-V measurements with metal-insulator-semiconductor (MIS) structures. It is found that the dielectric breakdown mechanism also depends on thickness. For relatively thick films (thickness >500 nm), the dielectric breakdown is electromechanical in origin, i.e. the dielectric strength is proportional to the square root of Young's modulus of the films. By scanning electron microscopy (SEM) observation, a microcrack in thicker films may contribute to a lower value of Young's modulus, which may confirm that the electromechanical breakdown is the dominant mechanism for dielectric breakdown of thicker films. In addition, the thickness dependent dielectric strength can be described by the well-known inverse power-law relation by using different exponents to describe different thickness ranges, However for thinner films, i.e., <500 nm, the experimentally observed relationships among the dielectric strength, Young's modulus, and film thickness cannot be explained by the existing models.

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Thickness dependent dielectric strength of a low-permittivity dielectric film

For the past ten years, organic materials have been extensively investigated as an electronic material for thin film transistor (TFT) devices. Organic materials offer strong promise in terms of properties, processing and cost effectiveness and they can be used in flat panel displays, imagers, smart cards, inventory tags and large area electronic applications. In this review, we summarize the current status of the organic thin film transistors including substrate materials, electrodes, semiconducting and dielectric layers; organic thin film preparation methods; morphological studies for organic thin films; electrical characterization of gate dielectric layers and semiconducting active layers; and characterization of the OTFTs. Future prospects and investigations required to improve the OTFT performance are also given.

Organic thin film transistors: Materials, processes and devices

Deposition of PTFE thin films by RF plasma sputtering on 〈100〉 silicon substrates

High-voltage lithium batteries have attracted increasing attention for large scale energy storage application in electric vehicles, smart grids and other electronic devices. However, a major bottleneck to achieve high-voltage lithium batteries is the anodic voltage stability of electrolytes. Herein, we fabricate a composite polymer electrolyte, comprised of poly(methylethyl α-cyanoacrylate), nonwoven polytetrafluoroethylene and lithium bis(oxalate)borate salt. The composite polymer electrolyte presents a wide electrochemical window, which is explored to address the above-mentioned bottleneck. It is demonstrated that such a composite polymer electrolyte exhibits a higher ionic conductivity (1.24 mS cm−1 at 25 °C), better dimensional thermal resistance (150 °C) and higher ion transference number (0.63) compared to those of commercially available liquid electrolytes with a polypropylene separator. In addition, LiNi0.5Mn1.5O4/Li batteries employing such a composite polymer electrolyte deliver excellent cycling performance and outstanding rate capability. So, it is demonstrated that the poly(methylethyl α-cyanoacrylate) based polymer electrolyte appears to be a promising candidate of high-voltage lithium battery electrolyte towards next generation high energy density batteries.

S.T. Li

Papers

Pulsed-laser deposition of crystalline Teflon (PTFE) films

Anisotropic resistivity in pulsed-laser deposited Bi 2 Sr 2 CaCu 2 O 8+δ films

In-situ reflectivity measurements during pulsed-laser deposition of Bi 2 Sr 2 CaCu 2 O 8+δ