The Effect of the Surface Layer on the Dielectric Constant of (Pb, La)TiO 3 Thin Films
- PDF / 1,192,020 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 97 Downloads / 170 Views
Z3.7.1
The Effect of the Surface Layer on the Dielectric Constant of (Pb, La)TiO3 Thin Films G.L. YU, D.Q. XIAO, L.L. MENG, P. YU, AND J.G. ZHU Department of Materials and Science Sichuan University Chengdu, 610064, China ABSTRACT: (Pb, La)TiO3 (PLT) ferroelectric thin films are one of the promising candidates for applications in dynamic random memory and pyroelectric detectors, etc. However, the chemical composition in the surface layer of thin films is usually different from that in the “bulk” region of the thin films. For instance, it has been reported that there is Pb, Ti, or La enrichment in the surface layer of the (Pb, La)TiO3 thin films. According to a numerical modeling using effectivemedium theory, which was developed in our group, we discussed the effect of the surface layer on the dielectric constant of (Pb, La)TiO3 thin films. The effect of Pb, Ti, or La enrichment in the surface layer on the dielectric constant of PLT thin films was discussed. And a case of the “upgraded” and the “down-graded” thin films was expatiated and discussed. INTRODUCTION In recent years, ferroelectric thin films have been attracting great attention because of their potential applications in dynamic random memory and pyroelectric detectors etc. Much research has been done on these thin films, of which the research of the effect of the surface and interface is significant, because the surface and interface play a very important role in deciding the properties of thin films. Some work indicated that the chemical compositions in the surface layer of the thin films were usually different from those in the “bulk” region of the thin films. For example, the Pb enrichment [1-2] and La [3] enrichment in the surface layer of the Pb1-xLaxTi1-x/4O3 (abbreviated to PLT) thin films have been reported. In our group’s previous work [4], a numerical modeling by using effective-medium theory to discuss the effect of the surface layer on the dielectric properties of these thin films had been mentioned and the results of the discussion on PbTiO3 according to the model are to be published. In this paper, we discuss the surface effect of (Pb,La)TiO3 thin films on the dielectric constant of the films according to the model. The effort of Pb or La enrichment in the surface layer on the dielectric constant of PLT thin films was discussed. And a case of the “up-graded” and the “down-graded” thin films was expatiated and discussed. OUTLINE OF THE MODEL USED The texture of the thin film is illustrated in figure 1. The whole thin film can be divided into six layers logically in the direction of depth: the top electrode, the top transition layer, the surface layer, the “bulk” region of thin film, the bottom transition layer and the bottom electrode in sequence. And the surface layer is made of the expected compound and the related oxide, which is illustrated by figure 2. For example, when we discuss Pb enrichment in the surface layer of PLT thin films, the PLT, according with the expected stoichiomestry, is the expected
Z3.7.2
compound and PbO is the un
Data Loading...
