AlGaAs diodes for X-ray spectroscopy

Al0.8Ga0.2As p+–p−–n+ diodes with low reverse leakage currents (<10 nA) were evaluated as room temperature (23 °C), soft X-ray photon-counting detectors. X-ray spectra from a 55Fe radioactive source show these diodes can be used for spectroscopy with promising energy resolution of 1.47 keV FWHM at 5.9 keV. At elevated reverse bias levels (>20 V), we observed avalanche multiplication which, while improving the signal-to-noise ratio, degraded the spectroscopic performance.