Novel Ultrafast Backscattered Electron Detector With Field-Effect Transistor Enhanced In Situ Signal Amplification

For electron microscopy, ultrafast detectors with high sensitivity are intrinsically demanded, especially for biomedical applications, where probing electrons can damage biological samples under investigation. Addressing this, a novel ultrafast electron detector with field-effect transistor (FET) enhanced in situ signal amplification is proposed and verified in this study. Through Silvaco-based simulation, the detector demonstrates a high gain of over sevenfold of the current generated in conventional p-i-n-based detectors and an ultrafast response with a cutoff frequency of over 500 MHz. Furthermore, a proposed nonuniform gating oxide design shows an improvement in the detector output current from 61 to$87 \mu \text{A}/\mu \text{m}$. Besides, a nonlinear doping profile of the electron absorption layer is also proven effective in enhancing the in situ signal amplification effects. Particularly, a detector with a thick electron absorption layer of$50 \mu \text{m}$exhibits excellent performances with an output current over$16 \mu \text{A}/\mu \text{m}$and a cutoff frequency of approximately 200 MHz, making it possible to detect high-energy electrons.