Silicon Carbide X-Ray detectors
Silicon Carbide X-Ray detectors
Silicon Carbide X-Ray detectors
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<strong>Silicon</strong> <strong>Carbide</strong> X-<strong>Ray</strong> <strong>detectors</strong><br />
Dr. John E. Lees<br />
PPARC Kite Club - Birmingham<br />
6 March 2007<br />
Space Research Centre
Introduction<br />
Limitation of silicon based <strong>detectors</strong><br />
cooling<br />
radiation damage<br />
Search for other materials – wide band gap<br />
GaAs<br />
Diamond<br />
<strong>Silicon</strong> <strong>Carbide</strong><br />
SiC imaging arrays<br />
Collaboration with University of Newcastle<br />
Space Research Centre
X-ray <strong>detectors</strong> for Space Applications:<br />
• Photon counting<br />
• Imaging<br />
• Good timing resolution<br />
• High spatial resolution<br />
• Solar blind – not sensitive to visible light<br />
• High quantum efficiency<br />
• High dynamic range<br />
• Low background<br />
• Radiation hard<br />
• Energy resolution<br />
SiC<br />
√<br />
√<br />
√<br />
√<br />
X<br />
√<br />
√<br />
√<br />
√<br />
√<br />
Space Research Centre
STSSD structure<br />
25 nm thermally<br />
grown SiO 2<br />
Semi-transparent Schottky<br />
contact.<br />
3 nm Ti / 12 nm Ni<br />
4nm Cr / 200nm Au<br />
n 4H-SiC<br />
n + 4H-SiC<br />
Lees et al.,<br />
Nucl. Inst. Meth A<br />
2007 In press<br />
5 nm Cr / 250nm Au 4nmCr/100nmNi<br />
Ohmic Contact<br />
20 μm epitaxial layer on a 370 μm substrate<br />
Space Research Centre
Semi-Transparent SiC Schottky Diode<br />
1.0x10 -3 cm -2 1.81x10 -3 cm -2<br />
4.93x10 -4 cm -2<br />
400μm<br />
LHS: A 280μm 2 Schottky contact and gold bond pad<br />
RHS: Die layout with a range of diode sizes<br />
Space Research Centre
Improving the Low Energy Response<br />
K-shell emission lines of elements: Na (Z=11, E=1.04 keV) to Zn (Z=30, E=8.64 keV)<br />
Space Research Centre
Low Energy X-ray Resolution<br />
Room Temperature Operation - 23 °C<br />
55<br />
Fe spectrum – 5.9 keV, FWHM 1.49 keV<br />
Space Research Centre
High Energy X-ray Resolution<br />
Room Temperature Operation 23 °C<br />
60 keV spectrum, FWHM 2.2 keV<br />
Space Research Centre
Energy Resolution<br />
~1/E dependence rather than ~1/E 0.5 for Fano limited case<br />
Space Research Centre
High Temperature Operation<br />
Bertuccio et al<br />
Nucl. Inst. Meth A<br />
380 (2004) 413<br />
Good resolution possible even at 100°C<br />
Space Research Centre
Uniformity<br />
Diode uniformity<br />
mapped at<br />
BESSY<br />
A 10μm x 10 μm X-ray spot (12 keV)<br />
Space Research Centre
Efficiency<br />
15μm depletion<br />
depth<br />
Measured and modelled efficiency<br />
Space Research Centre
Applications<br />
• X-ray analysis<br />
• Neutron imaging<br />
• Biomedical<br />
• Alpha particles & ions<br />
• Dosimetry<br />
• High Temperature Operation (≥ 100°C)<br />
• Hazardous Environments – Space, Nuclear, Well Logging<br />
Space Research Centre
Harsh Environments<br />
X-treme Radiation Environment<br />
Space Research Centre
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