SynopsisPolyamides were prepared by reacting 3,5-diamino benzoic acid (DAB) and/or 1,3-bis( 3-amino benzamido) benzene ( ABB ) with terephthaloyl chloride in N,N-dimethylacetamide. Five polymer samples having different contents of pendant carboxyl groups were prepared by changing the molar ratios of DAB : ABB in the initial monomer feed as 1 : 0 ( C ) , 3 : 1 ( C3A), 1 : 1 (CA) , 1 : 3 ( CA3), and 0 : 1 (A). The inherent viscosities of the polymers ranged from 0.198 to 0.478 dL/g. DSC and TG studies indicated loss in weight in the temperature range of 80-200°C due to absorbed moisture.The major loss in weight was observed above 400°C. The anaerobic char yield a t 800°C depended on the backbone structure and was found to range from 25 to 40%. The resistivities of polyamide film was determined a t 110 and 130°C and was found to decrease with an increase in carboxyl content. The dielectric constant of C and C3A polymer films was determined at frequencies ranging from 100 Hz to 1 MHz and at 110 and 130°C and was found to decrease with an increase in frequency or decrease in COOH content in the backbone.
Consistent attempts are being made to improve the resistivity of zinc oxide (ZnO) films for operating monolithic surface acoustic wave devices at low operational frequencies. This paper highlights a technique for diffusing lithium which is more viable, cleaner, and more compatible with silicon processing. Lithium is doped by bubbling oxygen through saturated Li2CO3 solution at different temperatures: Infrared and Auger electron spectroscopy reveal Li-O peaks. ZnO films with C-axis were deposited on SiO2 grown on single crystal silicon by RF magnetron sputtering. Resistivities of doped ZnO films at room temperature are one to two orders of magnitude higher than undoped ZnO films. These results are interpreted as a reduction in the donor states in ZnO, as Zn with its electron is ejected out. Si/SiO2 interface charges which are induced due to radiation effects during sputtering are annealed out during lithium doping, followed by an oxygen anneal.
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