Browsing by Author "Lim, WH"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    2nd generation microdosimeter with guard ring: an IBC study
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2009-11-25) Ziebell, AL; Hu, N; Lai, NS; Lim, WH; Reinhard, MI; Prokopovich, DA; Siegele, R; Dzurak, AS; Rosenfeld, AB
    Silicon-on-insulator (SOI) micro dosimeters have recently been used to successfully measure the radiobiological properties of mixed radiation fields typical of medical, space and radiation protection environments. These SOI devices consist of a 2D array of elongated parallelepiped diode structures. Charge collection studies have revealed that due to the electric field distribution within the planar SV, there are significant lateral charge diffusion effects which complicate charge collection and give rise to a less than ideal chord length variance. © 2009 AINSE
  • Thumbnail Image
    Item
    Cylindrical silicon-on-insulator microdosimeter: charge collection characteristics.
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2007-11-22) Ziebell, AL; Lim, WH; Reinhard, MI; Cornelius, IM; Prokopovich, DA; Siegele, R; Dzurak, AS; Rosenfeld, AB
    At present there exists a need, in both medical physics and radiation protection, for a portable microdosimeter that can be used in determining the radiobiological effectiveness (RBE) of different mixed radiation fields.
  • No Thumbnail Available
    Item
    Cylindrical silicon-on-insulator microdosimeter: design, fabrication and TCAD modeling
    (Institute of Electrical and Electronics Engineers (IEEE), 2009-04) Lim, WH; Ziebell, AL; Cornelius, IM; Reinhard, MI; Prokopovich, DA; Dzurak, AS; Rosenfeld, AB
    A novel silicon-on-insulator (SOI) microdosimeter has been designed and fabricated using planar processing techniques to realise a device with a micron-scale well-defined sensitive volume. Cylindrical structures were employed to allow for an improved definition of the average chord length of the sensitive volume over that of previous elongated parallelepiped solid-state detector designs. The structures were manufactured on individual silicon mesas situated on top of a buried oxide insulating layer. The mesa design eliminated lateral charge diffusion. Two kinds of test structures were designed with sensitive region widths of 2 mum and 10 mum. In addition, an array of 900 cylindrical diodes was fabricated to increase the charge collection statistics. TCAD (Technology Computer Aided Design) modeling of the electrostatic potential and electric field profile of the cylindrical microdosimeter was carried out to obtain 3D potential and electric field profiles. The modeling revealed a radial electric field within the cylindrical-shaped sensitive volume with a 1/r dependence. While the electric field at the core of the cylindrical microdosimeter was not sufficiently high to induce avalanche signal multiplication, the higher electric field at the core should still assist in the measurement of low linear-energy transfer (LET) events. © 2009, Institute of Electrical and Electronics Engineers (IEEE)
  • No Thumbnail Available
    Item
    Development and fabrication of cylindrical silicon-on-insulator microdosimeter arrays.
    (Institute of Electrical and Electronics Engineers (IEEE), 2009-06) Lai, NS; Lim, WH; Ziebell, AL; Reinhard, MI; Rosenfeld, AB; Dzurak, AS
    Recent developments in the fabrication and simulation of prototype silicon-on-insulator (SOI) microdosimeter arrays are presented. A new planar array design has been proposed which has a number of advantages over the previous elongated parallelepiped and cylindrical mesa array designs. This novel planar array design, which incorporates a guard ring, is based upon 2500 planar cylindrically shaped p-i-n detectors and was fabricated via dopant diffusion and ion implantation. The dopant-diffused arrays were successfully fabricated and tested using 2 mum and 10-mum- thick SOI substrates. Technology computer-aided design modeling of the ion-implanted structure is presented which includes the electrostatic potential profile, showing possible avalanche signal multiplication around the n+ core of the microdosimeter. The alpha particle charge transient response was simulated to determine the charge collection in the sensitive region. © 2009, Institute of Electrical and Electronics Engineers (IEEE)