Exoelectron emission in the pyroeffect regime in LiNbO3:Fe

Abstract

In monodomain single crystals LiNbO3:Fe during the pyroeffect the phenomenon of unipolar exoelectron emission with the energy of about 1 keV is observed within the temperature range of −50 to +170 °C. It is proposed that the mechanism of electron emission is based on the Malter effect. The identical physical grounds for existence of the temperature top limit (T = 170 °C) for observed electron emission and for the well‐known optical damage effect is stated. The calculation f the Debye screening length and of the pyroelectric field E is based on experimental results.

Electron emission from ferroelectrics

“…The ferroelectric phase transition is the region where all physical parameters such as structural symmetry, spontaneous polarization, pyroelectric coefficient, dielectric permittivity are changed critically. Anomalous photoemission was observed in monodomain ferroelectric monocrystals BaTiO 3 during all three well-known phase transitions, both in crystals [44][45][46] and thin films. 47 The photostimulated FEE current was asymmetric: The current from the Z ϩ face was almost twice as much as the current from the opposite polar face.…”

“…These charges produce an electrostatic field E in the vacuum gap, which according to the presented estimations 1 was as high as Eϭ1.35ϫ10 7 V/cm. The data by Rosenman and Boikova, 35 obtained by the use of LiNbO 3 : Fe, demonstrated a long-time persistent emission current which was ascribed to the dynamic equilibrium state between two processes: pyroelectric charge generation and bulk charge relaxation process. The upper temperature of FEE was Tϭ420 K, and it was ascribed to the activation of Fe ϩ2 -donor centers and correspondingly increasing the bulk conductivity.…”

“…The upper temperature of FEE was Tϭ420 K, and it was ascribed to the activation of Fe ϩ2 -donor centers and correspondingly increasing the bulk conductivity. 35 FEE was studied in detail by Rosenman, Rez, and co-workers 36,37 by the use of the isomorphic ferroelectric crystal LiTaO 3 ͓Fig. 3͑a͔͒.…”

“…This experimental setup was used in all works on ''weak'' FEE. 1,[35][36][37]42,[49][50][51][52][53][54][55][56][57][58] Two sorts of materials, ferroelectric crystals TGS and ferroelectric ceramics PLZT 7/65/35, will be considered. They differ strongly in the value of spontaneous polarization ( P s,PLZT / P s,TGS Ϸ10) and in the dielectric permittivity ( cr,PLZT / cr,TGS Ϸ50).…”

Low Voltage Electron Emission from BaTiO3 Thin Films Treated in Hydrochloric Acid

“…Electron emission from ferroelectric materials due to a large change in dielectric displacement has been studied for many years due to its potential application to vacuum electronic devices, like flat panel displays and bright electron guns [1,2]. Ferroelectric electron emission (FEE) is an unconventional electron emission effect which does not need an externally applied extraction field, since the field emission of the electrons is achieved by the spontaneous polarization field of the ferroelectric material itself.…”