Neutron irradiation of cold GaAs devices and circuits made with an ion-implanted monolithic process

We have irradiated with neutrons from SARA facility (Grenoble) four versions of cryogenic GaAs monolithic preamplifiers and one MESFET at 87 K. The preamplifiers were designed to readout the ionization signal from the LAr electromagnetic calorimeter of ATLAS experiment. In this paper, data on modification of preamplifier transfer function and degradation of noise performance with irradiation are presented. New preamplifiers (M- and D-versions) exhibited better resistance to irradiation than old C3 version, thanks to a better design of second stage. DC performance of MESFET has been well characterized before and after irradiation. Due to effects of carrier removal and mobility degradation, pinch-off voltage Vp and maximum drain current Idss dropped by factor 2.1 and 7.4, respectively, while the transconductance at standing current Id = 8 mA did not change after a fluence of about 13×1014neutronscm2 (1 MeV equivalent).