University of Twente Student Theses


High capacitance thin films

Chmiel, Christoph (2011) High capacitance thin films.

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Abstract:A capacitance test circuit using strontium titanate as dielectric material was produced by means of modern thin �lm deposition techniques. The capacitance per area was measured by using two di�erent measurement techniques. The quasistatic value was found to be C/A= 4.70 � 0.03 �F/cm2 and the value at a frequency of 1kHz was found to be C/A= 3.85 � 0.08 �F/cm2. A characterization of this �lms with the use of atomic force microscopy and x-ray di�raction was done. To increase this values even further, strontium doped barium titanate targets for the use in laser ablation systems were produced by using the solid state synthesis method at a temperature of 1200�. Since this material is normally sintered at higher temperatures an polyvinyl alcohol had to be used to produce stable targets. The purity of these targets was checked with a x-ray di�raction scan after each process step. Two types of stoichiometry were produced: Ba0.5Sr0.5TiO3 and Ba0.67Sr0.33TiO3. A crack was found in the latter one and so only the former could be tested in a laser ablation device. With a deposition temperature of 700� was the growth speed determined to be 0.037 nm/pulse in an 0.13 mbar oxygen atmosphere by using laser energy density of 1.5 J/cm2 from a KrF excimer laser operating at a wavelength of 248nm.
Item Type:Essay (Bachelor)
Faculty:TNW: Science and Technology
Subject:33 physics
Programme:Applied Physics BSc (56962)
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