Knowledge Exchange in AlGaAs X-ray detectors - resubmission

Lead Research Organisation: University of Leicester
Department Name: Physics and Astronomy

Abstract

The ideal detector for X-ray spectroscopy imaging system would have 100% detection efficiency, spatial resolution of a few microns, and spectral resolution of a few eV. It should also have low power consumption and be able to operate over a wide range of temperatures and in demanding radiation environments. In contrast, available Silicon X-ray detectors have low radiation tolerance limitations and demand thermal cooling for X-ray spectroscopy. Hence there is a need for detectors that have good spatial and energy resolution, good radiation tolerance and can operate at or above room temperature without the need for external cooling. For many spectroscopic applications high quantum efficiency for soft X-ray photons with incident energies between 1 and 10 keV is essential since it is in this range where the elements Na (Z = 11, Ek = 1.04 keV) to Zn (Z = 30, Ek = 8.64 keV) have their K-shell emission lines. New detectors based on wide bandgap (> 2 eV) semiconductor materials have potentials to overcome the spectroscopic, temperature, radiation and voltage limitations of silicon. AlGaAs is one such material and detectors based on this material could find applications in areas such as medical and small animal imaging, real time extremity dosimetry as well as environmental monitoring such as X-ray fluorescence analysis of oil contaminates. AlGaAs detectors should also be able to operate in harsh radiation environments such as those associated with oil exploration and volcanic studies as well as future planetary missions and/or landers. Over the last two years the two academic groups (Space Instrumentation Group, University of Leicester and the Avalanche Photodiode Group, University of Sheffield) have been exploring the use of wide band gap semiconductors for use as X-ray and UV photon counting detectors. The Leicester - Sheffield collaboration have fabricated and measured the properties of simple AlGaAs pin diodes. Having pioneered the use of AlGaAs sensors as room temperature X-ray detectors we now believe that it is timely to seek funds to accelerate the knowledge exchange between the two groups to maintain the hard won scientific and commercial lead. Centronic Limited is a SME which has a wide portfolio in radiation detectors for a range of demanding applications. The Company produces detectors for monitoring of alpha, beta, gamma, X-ray and neutron radiation. These detectors are designed to suit a wide range of demanding applications, however, these are primarily non-imaging or spectroscopic. Access to AlGaAs detectors will open new and commercially lucrative markets. They have recently expanded into the USA, opening a branch in Houston, Centronic LLC which will increase the technology transfer opportunities. The Knowledge Exchange aspects of this work are key objectives of the project and these will be developed in collaboration with the commercial partner, Centronic Ltd. Some of the Knowledge Exchange outcomes are summarised below: University of Leicester 1) Access to new technology for X-ray and particle detection 2) Understanding of semiconductor materials 3) Understanding of fabrication processes 4) Commercial and scientific opportunities unique to wide band gap semiconductors University of Sheffield 1) Access to expertise in high resolution X-ray detectors 2) Understanding of X-ray photon counting detectors 3) Understanding of spectroscopic imaging 4) Establishing a X-ray testing facility 5) New outlets for detectors - medical, automotive, and space instrumentation. Centronic Limited 1) Access to new technology 2) New market opportunities. in particular using radiation detectors for the oil industry, and healthcare. 3) New knowledge in imaging X-ray spectroscopy A successful project will produce sensors that have applications in many areas, with potential benefits for healthcare in the UK (through better medical senors) and environment studies.

Publications

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Barnett (2011) The temperature dependence of the avalanche multiplication process in Al 0.8Ga0.2As avalanche photodiodes at soft X-ray energies in INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT

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Barnett A (2014) Characterization of GaAs mesa photodiodes with X-ray and ?-ray photons in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

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Barnett A (2012) A varied shaping time noise analysis of Al0.8Ga0.2As and GaAs soft X-ray photodiodes coupled to a low-noise charge sensitive preamplifier in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

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Barnett A (2011) Modelling results of avalanche multiplication in AlGaAs soft X-ray APDs in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

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Barnett A (2011) The spectral resolution of high temperature GaAs photon counting soft X-ray photodiodes in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

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Barnett A (2011) Temperature dependence of the avalanche multiplication process and the impact ionization coefficients in Al0.8Ga0.2As in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

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Barnett A (2010) Temperature dependence of AlGaAs soft X-ray detectors in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

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Chee Hing Tan (2011) Avalanche Gain and Energy Resolution of Semiconductor X-ray Detectors in IEEE Transactions on Electron Devices

 
Description Compound semiconductor detectors can be used for high temperature X-ray spectroscopy
Exploitation Route Development of devices for research and commercial purposes
Sectors Aerospace, Defence and Marine,Healthcare,Transport

 
Description Dosimetry 
Organisation Nottingham University Hospitals NHS Trust
Department Medical Physics and Clinical Engineering (MPCE)
Country United Kingdom 
Sector Charity/Non Profit 
PI Contribution Expertise on radiation detectors
Collaborator Contribution Expertise in dosimeters in medical physics
Impact None at present
Start Year 2013
 
Description LRI 
Organisation Leicester Royal Infirmary
Country United Kingdom 
Sector Hospitals 
PI Contribution Expertise in X- and Gamma-Ray instrumentation
Collaborator Contribution Clincial expertise
Impact Publications Successful grant applications
Start Year 2011