Simulation of High-Temperature Performance and Electronic Noise of SiC-JFET for Charge-Sensitive Preamplifier

In special applications such as reactor in-core detection and deep space exploration missions, nuclear detection systems must contend with high-temperature environments. The temperature sensitivity of front-end electronics degrades detection system performance in high temperatures. This study proposes using silicon carbide junction field-effect transistors (SiC-JFETs) as input transistors of preamplifiers to reduce output noise at high temperatures. The theoretical analysis and Technology Computer Aided Design (TCAD) simulation were used to demonstrate how the electrical properties and noise contribution of SiC-JFET change with increasing temperature. Results show that SiC-JFET has a wider operating temperature range and fewer performance variations as the temperature rises from 300 to 675 K when compared to Si-JFET with the same structure. SiC-JFET always has lower noise than Si-JFET when the structures are identical. When the two devices have the same transconductance, SiC-JFET produces less noise at high temperature and long shaping time. Furthermore, the output noise of a nuclear spectrometer with SiC detectors and capacitance-matched JFETs was calculated and analyzed. When the temperature exceeds 324 K or the shaping time is longer than
$3.5~\mu \text{s}$
, SiC-JFET can obtain lower noise, and the equivalent noise charge (ENC) reduces thousands of electrons at most. This research lays the groundwork for building SiC-JFET-based charge-sensitive preamplifier (CSA) and front-end circuits with high-temperature resistance and low noise.