Characteristics of a silicon carbide field emission array under pre-breakdown conditions

This study assesses promising field electron sources based on silicon carbide monolithic field emission array (FEA). FEA is fabricated on single-crystal wafers of silicon carbide (0001C) 6$H$-SiC of $n$-type conductivity using the technology of two-stage reactive ion etching in SF$_6$/O$_2$/Ar atmosphere. To implement conditions close to breakdown, an experimental setup based on high-voltage narrow pulses generating device GKVI-300 was used. A series of nanosecond voltage pulses with amplitudes from 120 to 250 kV was generated. To study the characteristics of the FEA in the pre-breakdown state, the beam of field emitted electrons was separated from the ion torch or cathode plasma, formed in the following breakdown phases, by placing a 50-$\mu$m-thick titanium foil under zero potential into the interelectrode gap. Current-voltage characteristics of peak-currents vs. peak-voltages passing through the foil are close to rectilinear in the Fowler–Nordheim coordinates. The current-voltage characteristics plotted for each of the pulses along increasing and decreasing branches show a discrepancy (hysteresis). After the experiments, the silicon carbide cathode FEA was studied in a scanning electron microscope.