Investigation of the radiation damage of GaAs detectors by protons, pions and neutrons

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 1997-05, Vol.390 (1), p.33-40
• Main Authors: Lübelsmeyer, K., Arbabi, S., Braunschweig, W., Chu, Z., Krais, R., Kubicki, Th, Rente, C., Syben, O., Tenbusch, F., Toporowski, M., Wittmer, B., Xiao, W.J.
• Format: Article
• Language: English
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/S0168-9002(97)00339-2

Surface barrier detectors processed in Aachen using semi-insulating (SI) GaAs from several manufacturers have been irradiated with high fluences of neutrons (mean energy 1 MeV, fluence up to Φ n ∼ 5 × 10 14 cm −2), pions (191 MeV, fluence up to Φ π ∼ 0.6 × 10 14 cm −2) and protons (23 GeV, fluence up to Φ p ∼ 2 × 10 14 cm −2). The detectors have been characterized in terms of macroscopic quantities like I–V characteristic curves and charge collection efficiencies for incident minimum ionizing- (mip) as well as α-particles. All detectors work well after the exposure. At the highest fluences a sizable degradation in the charge collection efficiencies has been observed for all investigated materials. SI-GaAs material with low carbon (LC) content seems to be less affected than substrates with a higher carbon concentration. At the highest irradiation level the mip signal from a 250 μm thick detector made of LC material amounts to 8000 electrons (at 400 V bias voltage) independent of peaking times between 40 ns and 2.2 μs. The leakage currents for this material are even reduced after the irradiation.