Spectrometric properties of semi-insulating GaAs detectors irradiated by 5 MeV electrons at different dose rates

Abstract

The radiation hardness of Semi-Insulating (SI) GaAs detectors against 5 MeV electrons is investigated in this paper. The influence of two parameters, the accumulative absorbed dose (from 1 to 120 kGy) and the applied dose rate (20, 40 or 80 kGy/h), on detector spectrometric properties was studied. The electron irradiation has negatively affected the detector CCE (Charge Collection Efficiency). Un-irradiated detectors exhibited the CCE of 79% at maximum operating reverse voltage of 300 V and reached the maximum CCE of 51% at 200 V after irradiation by a dose of 120 kGy. Relative energy resolution was also affected by electron irradiation. Its global degradation was observed in the range of doses from 24 up to 120 kGy, where an increase from 19% up to 39% at 200 V reverse voltage was noticed. On the other hand, a global increase of detection efficiency with dose, by about 30% at 120 kGy, was observed with all samples. We did not observe any significant influence of chosen dose rates applied during irradiation on investigated spectrometric properties of detectors.

Radiation hardness limits in gamma spectrometry of semi-insulating GaAs detectors irradiated by 5 MeV electrons

“…Detectors investigated in this paper are the same samples as those studied and described in our previous papers [8][9][10][11][12]. The Schottky barrier detectors were made of a bulk VGF (Vertical Gradient Freeze) SI GaAs grade of 230 µm thickness with the circular Schottky electrode made of Ti/Pt/Au (10/35/90 nm) multilayer on the top and a whole area quasi-ohmic metal electrode from Ni/AuGe/Au (30/50/90 nm) multilayer on the back side of the substrate.…”

“…The CCE was determined from measured pulse-height spectra as it was described in paper [11] and its behaviour can be seen in figures 6 and 7. The CCE values were obtained as an arithmetic average of CCE of four detectors on one detector segment irradiated by the same dose rate.…”

“…Si; GaAs detectors achieve higher detection efficiency of γ-and X-rays. There are only a few studies dealing with radiation resistance of GaAs detectors against high-energy electrons [6][7][8][9][10][11][12], however they present promising results. Afanaciev et al irradiated the Cr-doped GaAs sensors by 10 and 8.5 MeV electron beam at a dose rate of 20 to 400 kGy/h to a total dose of 1.5 MGy and observed the charge collection efficiency (CCE) degradation with the absorbed dose [6].…”

“…Torres et al irradiated Cr-doped GaAs detectors by 22 MeV electrons to doses in range from 48 to 1550 kGy with 50 to 500 kGy/h dose rates and they noticed an increase of dark current and deterioration in CCE with increasing cumulative dose [7]. We have also studied the spectrometric and electrical properties of developed SI GaAs detectors influenced by high energy electron irradiation, however, in lower range of doses, from 1 kGy up to 200 kGy and at dose rates from 20 to 80 kGy/h before [8][9][10][11][12]. In this paper we are continuing in our radiation hardness study of SI GaAs detectors against 5 MeV electrons with cumulative doses up to 1000 kGy.…”

GaAs radiation-degraded detectors: gamma spectrometry at lowered temperatures

“…The shift of detected signal to lower channels in spectra expresses the deterioration of detector charge collection efficiency. Peak positions in measured gamma spectra (figure 5) were used to calculate the CCE using the method described in [13]. The CCE is shown in figure 6(a) together with the energy resolution of the detector related to the temperature of the detector.…”