Electron emission from ferroelectric thin films enhanced by the presence of 90° ferroelectric domains

In this work, a ferroelectric domain-enhanced electron emission mechanism is proposed. The polarization distribution near 90deg domain walls is calculated by solving a set of second order differential equations, including the Poisson´s one and equations derived from an expansion of the free energy Phi(P) in power series of the polarization according to the Devonshire-Landau-Ginzburg theory. Domain walls intersecting the emitting surface cause sufficient electric fields and lower the potential barrier for electron emission. This induces centers of enhanced electron emission. Relaxing domain walls were found to excite trapped excess electrons in front of the wall.