Dual-Functional Ni/4H-SiC Schottky Interfaces: Robust UV and X-ray Detection, Imaging in Extreme Environments

초록

Wide-bandgap (WBG) semiconductors are increasingly investigated for optoelectronic applications requiring stability under harsh electrical and radiation conditions. Among them, 4H-SiC, with its high thermal conductivity, strong radiation tolerance, and large critical electric field, is particularly attractive for ultraviolet (UV) and X-ray sensing. In this work, Ni/4H-SiC Schottky barrier diodes (SBDs) were fabricated and comprehensively examined through electrical, defect, optical, and radiation-response analyses. Forward current density-voltage (J-V) characteristics revealed efficient carrier transport, while reverse bias operation demonstrated a breakdown voltage (BV) exceeding 1 kV. Deep-level transient spectroscopy (DLTS) identified two dominant defect states, Z(1/2) (E-C-0.664 eV) and EH6/7 (E-C-1.54 eV), governing charge transport and leakage behavior. Under UV illumination, the devices exhibited a responsivity of 0.13 A/W and external quantum efficiency (EQE) of 64.8% at -5 V, with visible-light rejection ratios >10(3). X-ray testing across dose rates from 0.1 to 3.8 mGys(-1) confirmed linear photocurrent scaling, while high-energy radiation measurements spanning diagnostic (similar to 100 kVp) to therapeutic (6-15 MV) X-rays and electron beam (6-20 MeV) demonstrated stable charge collection and reproducible response (RSD < 10%). These results confirm the strong radiation hardness and electrical stability of Ni/4H-SiC SBDs, highlighting their potential for dual-mode UV and high-energy radiation detection in environments where ionizing radiation or high-voltage stress limit the use of conventional semiconductors.

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