Two custom-made Al0.2Ga0.8As p+-i-n+ mesa X-ray photodiodes (200?µm diameter, 3?µm i layer) have been electrically characterised across the temperature range -20?°C to 60?°C. The devices were connected to a custom-made charge sensitive preamplifier to produce an AlGaAs photon-counting X-ray spectrometer. The devices' responses to illumination with soft X-rays from an 55Fe radioisotope X-ray source (Mn Ka?=?5.9?keV; Mn Kß?=?6.49?keV) were investigated across the temperature range -20?°C to 20?°C. The best energy resolution (FWHM at 5.9?keV) achieved at 20?°C was 1.06?keV (with the detector at 10?V reverse bias). Improved FWHM was observed with the devices at temperatures of 0?°C (0.86?keV) and -20?°C (0.83?keV) with the photodiode reverse biased at 30?V. The average electron hole pair creation energy was experimentally measured and determined to be 4.43?eV?±?0.09?eV at 20?°C, 4.44?eV?±?0.10?eV at 0?°C, and 4.56?eV?±?0.10?eV at -20?°C.
Funding
STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCIL; ST/P001815/1
In situ X-ray Fluorescence Spectroscopy for Deep Sea Mining Applications; G1537; STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCIL; ST/M004635/1