Low-voltage electron emission from thin [Pb(Mg1/3Nb2/3)O3]0.72 [PbTiO3]0.28 single crystals induced by ferroelectric polarization switching

Abstract

Electron emission from [Pb(Mg1/3Nb2/3)O3]0.72 [PbTiO3]0.28 (PMN–PT) thin ferroelectric single crystals is reported at ultralow voltages down to 20 V per 400 μm thickness, and for up to 109 switching cycles. The PMN–PT samples were prepared with split gold top electrodes exhibiting a 25 μm wide gap region. Applying a sinusoidal voltage between the two top electrodes and the bottom electrode initiated electron emission from the gap region. The emitted electrons were collected under UHV conditions using two single electron counters arranged under an angle of 90°. Two emission regimes have been identified. Both are attributable to weak electron emission, however, clearly separated by the onset of complete ferroelectric polarization switching. This is also confirmed by recording nanoscale ferroelectric hysteresis loops by means of piezoresponse force microscopy. The emitted electrons are found to have a broad energy distribution with the maximum kinetic energies reaching 110 and 50 eV for applied switching voltages of 140 and 110 V, respectively. Our results confirm that polarization reversal is the governing mechanism behind the electron-emission process in the thin PMN–PT samples. Also, the applied electric field strengths needed to trigger electron emission from the PMN–PT crystals are about 10 times lower compared to most other (ferroelectric) materials reported in the literature.