High Resolution Metal-Oxide-4H-SiC Radiation Detectors: A Review

This paper reviews the performance of vertical metal-oxide-semiconductor (MOS) radiation detectors on n-type 4H-SiC epitaxial layers, comparing SiO
₂
, Y
₂
O
₃
, and Ga
₂
O
₃
oxide layers. While the fabrication of conventional Schottky barrier detectors (SBDs) is much simpler, MOS detectors allow higher bias voltages, achieving full depletion in thick epitaxial layers. Fully depleted thick epitaxial layers pose larger attenuation to penetrating radiation such as X-/gamma-rays and neutrons enabling efficient and high-resolution detection. Hence, 4H-SiC based MOS detectors directly address the quest of developing radiation hard detectors suitable for penetrating radiation in harsh environments such as nuclear reactor cores and space missions. All the MOS detectors discussed in this study demonstrated excellent rectification properties with the Y
₂
O
₃
MOS detectors showing the lowest reverse biased leakage current. Y
₂
O
₃
MOS detectors also showed the highest resolution and charge collection efficiency (CCE) in self-biased mode even when compared to a benchmark Ni/4H-SiC SBD. All the MOS detectors showed high energy resolution at optimized bias for 5486 keV alpha particles. The 0.29% energy resolution of the benchmark SBD is attributed to substantially lower Z
_1/2
and EH
_6/7
trap concentrations in the 4H-SiC epilayers than those in the MOS detectors. The study emphasizes suppressing lifetime-killer trap centers such as Z
_1/2
and EH
_6/7
for enhanced detector performance and underscores the need for further investigation into surface passivation mechanisms and their impact on junction properties.