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Electron detection at low energy range for scanning electron microscope (SEM), electron capture detector and electron probe micro-analysis (EPMA) applications, require detectors with high sensitivity and accuracy for low energy range. Such detectors must therefore have a thin entrance window and low recombination at the Si-SiO 2 interface. An electron detector with 100% photons to electron-hole pair production rate having a 10 nm SiO 2 passivating layer reveals a responsivity of approximately 0.25 A/W when irradiated. Simulations results showing the responsivity of electron interaction between detectors of varied interface fixed oxide charge density Q f show that there is an appreciable difference with the responsivity of a p + n detector and that of an n + p. The simulation results also show the significance of the effect of the minority carriers transport velocity S n,p on the responsivity of the detector.

Silicon detectors made on p-substrates are expected to have a better radiation hardness as compared to detectors made on n-substrates. However, the fixed positive oxide charges induce an inversion layer of electrons in the substrate, which connects the pixels. The common means of solving this problem is by using a p-spray, individual p-stops or a combination of the two. Here, we investigate the use of field plates to suppress the fixed positive charges and to prevent the formation of an inversion layer. The fabricated detector shows a high breakdown voltage and low interpixel leakage current for a structure using biased field plates with a width of 20 µm. By using a spice model for simulation of the preamplifier, a cross talk of about 1.6% is achieved with this detector structure. The cross talk is caused by capacitive and resistive coupling between the pixels.

This paper explores an alternative to the standard method of studying the responsivities (the input-output gain) and other behaviours of detectors at low electron energy. The research does not aim to compare the results of differently doped n C p detectors; its purpose is to provide an alternative characterization method (using scanning electron microscopy) to those used in previous studies on the responsivity of n C p doped detectors as a function of the electron radiation energy and other interface parameters.

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