Energy response characterization of InGaP X-ray detectors

Abstract

Two custom-made In0.5Ga0.5P p + -i-n + circular mesa spectroscopic X-ray photodiodes with different diameters (200 m and 400 m) and a 5 m i layer have been characterized for their response to X-ray photons within the energy range 4.95 keV to 21.17 keV. The photodiodes, operating uncooled at 30 °C, were coupled, in turn, to the same custom-made charge-sensitive preamplifier. X-ray fluorescence spectra of high-purity calibration foils excited by a Mo target X-ray tube were accumulated. The energy resolution (Full Width at Half Maximum) increased from 0.79 keV ± 0.02 keV at 4.95 keV to 0.83 keV ± 0.02 keV at 21.17 keV, and from 1.12 keV ± 0.02 keV at 4.95 keV to 1.15 keV ± 0.02 keV at 21.17 keV, when using the 200 m and 400 m diameter devices, respectively. Energy resolution broadening with increasing energy was attributed to increasing Fano noise (negligible incomplete charge collection noise was suggested); for the first time the Fano factor for In0.5Ga0.5P was experimentally determined to be 0.13, suggesting a Fano limited energy resolution of 145 eV at 5.9 keV. The charge output of each system had a linear relationship with photon energy, across the investigated energy range. The count rate of both spectroscopic systems increased linearly with varying X-ray tube current up to ~10 5 photons s -1 cm -2 incident photon fluences. The development of In0.5Ga0.5P based spectrometers is particularly important for hard X-/ -ray astronomy, due to the material's large linear X-ray and -ray absorption coefficients and ability to operate uncooled at high temperatures.

The response of thick (10 μm) AlInP x-ray and γ-ray detectors at up to 88 keV

“…3; it was found to be 6 ± 5 e − rms (9 ± 5 e − rms, including the package) and 9 ± 5 e − rms (11 ± 5 e − rms, including the package) for D1 and D2, respectively, at 150 V applied reverse bias and 2 μs shaping time. For comparison, this is broadly similar to other high quality wide bandgap x-ray detectors operated at the same temperature, e.g., 13 e − rms for a 10 μm thick GaAs photodiode 9 and ≤8 e − rms for a 5 μm i layer thick InGaP photodiode 14 under their normal operating conditions and at a temperature ≈ 30 °C.…”

“…The Fano noise was estimated to be 138 eV (11 e − rms) at 4.95 keV and 285 eV (23 e − rms) at 21.17 keV, given an electronhole pair creation energy of 5.31 eV at 30 °C37 and, since the Fano factor of AlInP has not yet been reported, assuming a Fano factor of 0.13 (i.e., equal to that measured for In 0.5 Ga 0.5 P, 14 a similar wide bandgap ternary compound semiconductor). The difference between the measured FWHM at each energy and the expected Fano noise was attributed to the electronic noise and, if present, any incomplete charge collection noise.…”

“…Although the energy resolutions achieved with high quality cooled Si and Ge x-ray and γ-ray detectors coupled to ultra-low-noise front end electronics are close to their theoretical limits, [1][2][3] other semiconductor materials, such as SiC, 4,5 GaAs, [6][7][8][9][10] AlGaAs, [11][12][13] In 0.5 Ga 0.5 P, 14,15 and CdZnTe, 16,17 are under active development for use in the applications, which require high temperature tolerant, radiation hard, and/or high detection efficiency detectors. A variety of semiconductor radiation detectors have been, and are being, developed to meet the requirements of various applications that predominantly require the deployment of such instrumentation in harsh environments (e.g., spaceflight, nuclear science and engineering, and defense systems).…”

High temperature (≤ 160 °C) X-ray and β− particle diamond detector

“…Among the different requirements, high temperature and intense radiation tolerance play important roles when selecting detector materials for harsh environments. Wide bandgap semiconductor radiation detectors which have been investigated for use in such environments include GaAs [5][6][7][8], SiC [9][10][11], GaN [12][13], AlGaAs [14][15], AlInP [16][17][18], InGaP [19][20], CdTe and CdZnTe [21][22], HgI2 [23], ThBr [24], and diamond.…”

GaAs/Al0.8Ga0.2As separate absorption and multiplication region x-ray spectroscopic avalanche photodiodes

“…Due to the limitations of narrow bandgap (typically Si) X-ray spectrometers commonly in use today [1,2], a variety of wide bandgap materials, such as GaAs [3][4][5][6][7], diamond [8,9], SiC [10][11][12], In0.5Ga0.5P [13,14], Al0.52In0.48P [15][16][17], and AlxGa1-xAs [18][19][20][21], have been investigated as potential X-ray detector replacements. The cooling systems and radiation shielding often required for Si X-ray spectrometers [22] place substantial burdens on spacecraft mass, volume, and power consumption, limiting their suitability for certain space science applications (e.g.…”