Electron beam induced current imaging of ferroelectric thin films

We have observed Electron Beam Induced Current imaging of thin film ferroelectrics. The Electron beam irradiation of a thin ferroelectric film creates a local temperature gradient that induces a polarization gradient and therefore a local electric field. Although the temperature difference is small the gradient is on the order of thousands K/cm and results in a corresponding electric field of a few MV/cm. The thermally induced electric field drives the electron beam created carriers toward an electrode thus inducing an externally measurable current. Despite the very small carrier life time (<1 ns) in ferroelectrics, the induced electric field is strong enough to collect carriers from a few hundred nm depth before recombination. An EBIC gain of 5 to 20 was measured experimentally with BaTiU3 and LiTaOj films on silicon substrates. This method is insensitive to charge traps and provides a resolution better than l um.