Permanent polarization and charge injection in thin anodic alumina layers studied by electrostatic force microscopy

• Published in: Journal of applied physics Vol. 91; no. 11; pp. 9161 - 9169
• Main Authors: Lambert, J., Guthmann, C., Ortega, C., Saint-Jean, M.
• Format: Journal Article
• Language: English
• Published: 01.06.2002
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.1466529

An electrostatic force microscope (EFM) and a Kelvin probe are used to characterize the charges embedded in thin anodic alumina layers of thickness ranging from 100 to 400 nm. Introducing a method for obtaining self-supported alumina layers, we exhibit the presence of positive charges at the metal/oxide interface of anodic alumina layers. These positive charges, together with the negative charges present at the surface of the anodic layer, induce a true polarization of the layer. The magnitude of this polarization depends on the conditions of preparation of the layers and can be well controlled. As a second step, we show the influence of this polarization on charge injection in these layers with EFM: charges of both signs may be injected in unpolarized layers whereas one cannot inject negative charges in polarized layers, which thus exhibit a diode-like behavior.