Browsing by Author "Stevens Kalceff, MA"

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    Charge trapping and defect segregation in quartz
    (AIP Publishing, 1999-06-14) Stevens Kalceff, MA; Thorogood, GJ; Short, KT
    Irradiation induced charging of wide band gap materials may significantly influence the development of radiation damage and associated defect migration. Charge trapped at irradiation induced and/or pre-existing defects induces a localized electric field within the irradiated volume of specimen. The powerful combination of cathodoluminescence microanalysis and electric force microscopy allows direct monitoring of the development of the irradiation induced charge distribution and its effect on the microscopic spatial segregation of defects. These techniques have been used to demonstrate the important influence of the induced local field on the microscopic defect structure of quartz. © 1999 American Institute of Physics
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    Investigation and modeling of electric field gradients by electric force microscopy (EFM)
    (CRC Press, 2000-07-08) Thorogood, GJ; Short, KT; Stevens Kalceff, MA
    Electric Force Microscopy (EFM) is a relatively new and and powerful method of Scanning Probe Microscopy. It can be used to study electric field gradients on a microscopic scale e.g. trapped charge in quartz [1]. EFM images are generated by monitoring the changes in the phase of a vibrating metal coated cantilever interacting with the local electric field at the sample surface. Qualitatively the phase shift is related to the strength of the field and its ability to dampen the vibration of the cantilever. Quantification of the observed phase shift due to the magnitude of the field depends on resonance properties such as spring constant and the coating for each individual tip. In an attempt to better understand the relationship between the static charge in the surface and the probe work has been performed with an electric field standard. [2] The standard was composed of a patterned metal layer on a flat alumina substrate with an alumina film of thickness approximately 1 μm applied over the metal layer. This was to ensure the metal layer was insulated and conduction between them and the probe could not occur, which would lead to loss of charge. A wire was attached to an uncoated area on the metal layers to allow them to be positively charged. The charge was supplied by a power which was capable of generating different wave functions at different frequencies and voltages. EFM images where then collected in the area immediately above the metal layers and away from the metal layers to view the effect of vertical and horizontal separation on the interaction between tip and sample. The standard performed relatively well but its surface was very rough, which affected the phase images. A second standard has been made using silicon oxide as the substrate to allow the conducting layers on the surface to be produced using electron beam lithography. By removing the interaction of the surface with the tip and by using a standard with known properties we can investigate the interaction between the cantilever and the electric field. References [1] Stevens Kalceff M A, Thorogood G J and Short K T., 1999 J App Phys. [2] Thorogood G J, Short, K T and Stevens Kalceff M A, 2000 Proc 16th Australian Conf. on Electron Microscopy p121 © 2000 Informa UK Limited