Investigation of pyroelectric electron emission from monodomain lithium niobate single crystals

Abstract

The behaviors of thermally stimulated electron emission from pyroelectric monodomain lithium niobate single crystal (LiNbO 3) were investigated by utilizing a Si p–n junction photodiode as electron detector and a receptive electron beam resist (E-beam resist) as electron collector. In high vacuum (10 −6 Torr), the pyroelectric electron emission (PEE) was found to depend on the exposed emitting polar crystal surface (+ Z face or − Z face) and was significantly influenced by the emitter-electron receiver gap distances. Thus, the PEE from + Z face was detected during heating and was activated, in small gaps (<2 mm), by field emission effect on which was superposed an intense field ionization effect that primed intermittent runway ionizations (plasma breakdown into a glow discharge). In large gaps (>2 mm) the emission was simply mastered by field emission effect. Whereas, The PEE from − Z face was detected during cooling and was solely due to the field ionization effect. Therewith, for small gaps (<2 mm) the emission was governed by intermittent runway ionization ignitions resulting from a high ionization degree leading to dense plasma formation, and for large gaps (>2 mm) PEE was governed by field ionization generating a soft and continuous plasma ambient atmosphere. Significant decrease of electron emission current was observed from + Z face after successive thermal cycles. A fast and fully emission recovery was established after a brief exposure of crystal to a poor air vacuum of 10 −1 Torr.