X-/γ-ray photon counting spectroscopy with an AlInP array

An AlInP 3 x 3 pixel monolithic array was fabricated from a p(+)-i-n(+) structure wafer (6 mu m thick i layer) grown by metalorganic vapour phase epitaxy; each pixel (square mesa photodiode) had an area of 200 mu m x 200 mu m. The pixels were initially electrically characterized and were then subjected to illumination by X-ray and gamma-ray photons of energies <= 88 keV while each of them was in turn coupled to a custom-made, low noise, charge-sensitive preamplifier. The photon counting X-/gamma-ray spectroscopic performance of the pixels was investigated by obtaining and analysing Fe-55 X-ray, Am-241 X-/gamma-ray, and Cd-109 X-/gamma-ray spectra; the energy resolution (Full Width at Half Maximum), when the array and preamplifier were operated at the maximum investigated temperature (100 degrees C), was 1.54 keV +/- 0.08 keV at 5.9 keV, 1.58 keV +/- 0.08 keV at 22.16 keV, and 1.57 keV +/- 0.08 keV at 59.54 keV. This work sets the agenda for future development of an AlInP photon counting X-/gamma-ray spectroscopic imager for uncooled operation in high temperature environments.

Automated summary

An AlInP pixel array was fabricated and investigated for photon counting X-/gamma-ray spectroscopic performance, demonstrating high energy resolution at the maximum investigated temperature. This work sets the foundation for future development of an uncooled AlInP photon counting X-/gamma-ray spectroscopic imager for operation in high temperature environments.