Evaluation of Radiation Hardness of High-Voltage Silicon Vertical JFETs

TL;DR

This study evaluates the radiation hardness of silicon vertical HV-JFETs for use in high-radiation environments like the ATLAS Inner Tracker, combining experimental neutron irradiation tests with TCAD simulations to understand post-irradiation behavior.

Contribution

It provides the first detailed static characterization and physics-based simulation analysis of irradiated silicon HV-JFETs for high-radiation applications.

Findings

Pre-irradiation tests confirmed device functionality.

Neutron irradiation affected device electrical characteristics.

TCAD simulations offered insights into post-irradiation physics.

Abstract

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.