Thick 4H-SiC-Based Schottky-Type Electron Detector for Fast Microscopy and Extended Sensitivity to Sub-keV

Abstract

A defining trend in modern electron microscopy is the shift toward low-energy, low-current techniques to facilitate non-destructive, in-situ analysis at the frontiers of science. This work presents a novel strategy based on wide band-gap 4H-SiC for sensitive direct electron detection, featuring an ultra-thin Schottky entrance window and a thick $10^{\mathbf {{13}}}$ cm-3-level n- type epitaxial layer for low parasitic parameters.The detector achieves an ultra-low dark current of 0.06 pA and enables direct electron detection above 2 keV, with extended sensitivity down to 0.5 keV via a surface-charge compensation mechanism and minimum detectable beam current of 0.4 pA. Excellent linearity over a broad range of electron-beam current and energies has also been observed. Furthermore, the fast dynamic response within 1.0 ns has enabled the spatial resolution in morphology analysis with evident element-number-related features, by decoding time-domain signals into spatial intensity profiles. Together with the radiation stability under 2-hour continuous electron beam irradiation at 30 kA/cm2 and 20 keV, this work offers an attractive strategy for electron detection with high sensitivity and harsh environment ruggedness.