High temperature AlInP X-ray spectrometers

Two custom-made Al_0.52In_0.48P p⁺-i-n⁺ mesa photodiodes with different diameters (217 µm ± 15 µm and 409 µm ± 28 µm) and i layer thicknesses of 6 µm have been electrically characterised over the temperature range 0 °C to 100 °C. Each photodiode was then investigated as a high-temperature-tolerant photon counting X-ray detector by connecting it to a custom-made low-noise charge-sensitive preamplifier and illuminating it with an ⁵⁵Fe radioisotope X-ray source (Mn Kα = 5.9 keV; Mn Kβ = 6.49 keV). At 100 °C, the best energy resolutions (full width at half maximum at 5.9 keV) achieved using the 217 µm ± 15 µm diameter photodiode and the 409 µm ± 28 µm diameter photodiode were 1.31 keV ± 0.04 keV and 1.64 keV ± 0.08 keV, respectively. Noise analysis of the system is presented. The dielectric dissipation factor of Al_0.52In_0.48P was estimated as a function of temperature, up to 100 °C. The results show the performance of the thickest Al_0.52In_0.48P X-ray detectors so far reported at high temperature. The work has relevance for the development of novel space science instrumentation for use in hot space environments and extreme terrestrial applications.