  In the future ATLAS Inner Tracker, each silicon strip module will be equipped
with a switch able to separate the high voltage supply from the sensor in case
the latter becomes faulty. The switch, placed in between the HV supply and the
sensor, needs to sustain a high voltage in its OFF state, to offer a low
resistance path for the sensor leakage current in the ON state, and be
radiation hard up to 1.2e15 neq/cm2 along with other requirements. While GaN
JFETs have been selected as suitable rad-hard switch, a silicon vertical
HV-JFET was developed by Brookhaven National Laboratory as an alternative
option. Pre-irradiation results showed the functionality of the device and
proved that the silicon HV-JFET satisfied the pre-irradiation requirements for
the switch. To assess its suitability after irradiation, a few p-type HV-JFETs
have been neutron irradiated at Jozef Stefan Institute (JSI, Ljubljana,
Slovenia). This paper reports the static characterization of these irradiated
devices and the TCAD numerical simulations used to get an insight of the
physics governing the post-irradiation behaviour.
