Strathprints Home | Open Access | Browse | Search | User area | Copyright | Help | Library Home | SUPrimo

Development of low-pressure vapour-phase epitaxial GaAs for medical imaging

Bates, RL and Manolopoulos, S and Mathieson, K and Meikle, A and O'Shea, V and Raine, C and Smith, KM and Watt, J and Whitehill, C and Pospisil, S and Wilhelm, I and Dolezal, Z and Juergensen, H and Heuken, M (1999) Development of low-pressure vapour-phase epitaxial GaAs for medical imaging. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 434 (1). pp. 1-13. ISSN 0168-9002

Full text not available in this repository. (Request a copy from the Strathclyde author)

Abstract

A summary is given of progress accomplished with the development of low-pressure vapour-phase epitaxial GaAs as a material for X-ray detectors. As the III–V concentration ratio is altered from Ga-rich to As-rich, the material is shown to improve from p-type, to n-type with compensation via deep levels, to n-type with a doping density of 1.7×1014 atoms cm−3. The measured barrier height is 0.8 V, as expected for the Ti contact used. Overdepletion was obtained before breakdown, enabling a layer thickness of m to be deduced for the final sample. For the later samples, charge collection for 60 keV Am-241 gammas was bias independent at a value of 100±8%. Spectra were also obtained from Sr-90 electrons. The most probable value of the charge collected as a function of the bias reached a plateau and from this value a depletion width of m was found for the final sample, equal to the epitaxial layer thickness. Results from detailed alpha and low-energy proton spectroscopy are shown for diodes fabricated from this material. A charge collection efficiency of 100% was obtained when the diode could be depleted sufficiently. The concept of a charge collection depth was introduced, since a significant amount of charge was collected without bias. The minimum depth of such a region was shown to be m at 0 V reverse bias, far greater than the m predicted for the depletion depth. Charge coupling between the guard ring and the pad was observed and successfully modelled.

Item type: Article
ID code: 37498
Notes: 6th International Workshop on Gallium Arsenide and Related Compounds, PRAGUE, CZECH REPUBLIC, JUN 22-26, 1998
Keywords: epitaxial GaAs , medical imaging, vapour-phase epitaxial GaAs, Therapeutics. Pharmacology, Instrumentation, Nuclear and High Energy Physics
Subjects: Medicine > Therapeutics. Pharmacology
Department: Faculty of Science > Institute of Photonics
Faculty of Engineering > Civil and Environmental Engineering
Faculty of Science > Strathclyde Institute of Pharmacy and Biomedical Sciences
Related URLs:
    Depositing user: Pure Administrator
    Date Deposited: 08 Feb 2012 16:09
    Last modified: 05 Sep 2014 15:03
    URI: http://strathprints.strath.ac.uk/id/eprint/37498

    Actions (login required)

    View Item