Hard X-ray test and evaluation of a prototype 32×32 pixel gallium–arsenide array

Fabrication study of GaAs mesa diodes for X-ray detection

“…[1][2][3][4], but is slightly higher than one of the lowest dark current densities in the literature, 5.6 nA/cm 2 at 50 V at room temperature [5]. The very low dark current density in [5] Although each of our three samples with partially etched diodes show reasonably uniform dark currents, the mean dark currents from the three samples do differ in magnitude. While this observation is consistent with previous works [1][2][3], there has been no discussion on this in the literature.…”

“…Later, Kostamo et al fabricated a GaAs p-i-n diode array using dry etching and passivated the etched diodes with dielectric materials, which yielded dark current density between 40 and 400 mA/cm 2 [3]. These values are much higher than the dark current density of 5.6 nA/cm 2 reported by Erd et al [5], whose array consisted of 32 × 32 GaAs p-i-n diodes with partially-etched mesa (p layer removed between pixels) and guard rings.…”

High temperature GaAs X-ray detectors

“…14 Thicker devices would result in a lower capacitance, which has a direct effect in reducing the white series, 1/f, and dielectric noises. Also, future device passivation may reduce the surface component of the leakage current and its parallel white noise contribution, improving the X-ray performance of the devices.…”

“…Later devices with similar structure but thicker epilayer (325 lm) had an energy resolution of 0.300 keV FWHM at 5.9 keV, at room temperature. 14 However, it should be noted that such good energy resolutions have not since been replicated by other researchers (Refs. 12 and 14 had multiple authors in common) despite significant international effort.…”

Temperature dependent characterization of gallium arsenide X-ray mesa p-i-n photodiodes

“…10 in a 32 Â 32 pixel array have been reported with an energy resolution of 0.3 keV FWHM at 5.9 keV at room temperature. 11 Research has also been conducted on GaAs p þ -i-n þ mesa Xray photodiodes. High temperature (up to 90 C) X-ray detection characterization of GaAs p þ -i-n þ diodes (2 lm thick i-layer) has been reported.…”