Two emission modes from ferroelectric emitters

In recent years, ferroelectric emitters have received considerable attention. There are a number of applications for these devices including triggering gas switches to illuminating flat screen displays. There is still, however, controversy surrounding the nature of the emission process. One explanation is that the emission is due to the repulsion of surface screening electrons when the polarization is rapidly switched. The other is that the electrons are emitted from a surface plasma initiated at metal-insulator boundaries. Here, the authors report observations which demonstrate clearly for the first time that both types of emission can occur from the same sample and that the charge densities emitted are very similar