Stability of Charge Collection Efficiency and Time Resolution in 4H-SiC PIN Diodes Under X-ray Irradiation

TL;DR

This paper demonstrates that 4H-SiC PIN diodes maintain stable charge collection efficiency and timing resolution even after exposure to 2 MGy of X-ray radiation, indicating high radiation tolerance for demanding applications.

Contribution

It provides comprehensive characterization showing the radiation hardness of 4H-SiC PIN diodes up to 2 MGy X-ray dose, including minimal degradation in electrical and timing performance.

Findings

Leakage current remains ultralow after irradiation

Charge collection efficiency decreases by less than 5%

Timing resolution remains below 35 ps after irradiation

Abstract

This study evaluates the radiation tolerance of a 4H-SiC PIN detector under X-ray irradiation up to \SI{2}{MGy} (Si) at \SI{160}{keV}. The detector features a fully epitaxial vertical PIN structure with mesa terminations and field plates. Comprehensive pre- and post-irradiation characterization includes I-V/C-V measurements, charge collection efficiency (CCE) and timing resolution tests using $\beta$-particles ($^{90}$Sr). After \SI{2}{MGy} irradiation, the reverse leakage current remains at an ultralow level of $\sim 10^{-11}$ \si{A/cm^2} at \SI{-300}{V} with negligible degradation. C-V characteristics are basically consistent, with full depletion at \SI{~130}{V}. CCE for $\beta$-particles decreases by less than 5\%. The detector maintains good timing resolution: \SI{21}{ps} before and \SI{31}{ps} after irradiation, with jitter increasing moderately. These results demonstrate stable performance under extreme X-ray exposure, highlighting the detector's potential for radiation-hard applications in high-energy physics, space missions, and nuclear reactor monitoring.