The effect of Mg doping on the dielectric and tunable properties of Pb0.3Sr0.7TiO3 thin films prepared by sol–gel method

Xiaohua Sun,Meiya Li,Tianyou Peng,Jun Zou,Shuang Hou,Caihua Huang,Xing-Zhong Zhao,Xiuneng Li

doi:10.1007/s00339-013-7645-z

Abstract

Mg doped Pb0.3Sr0.7TiO3 (PST) thin films were fabricated by the sol–gel method on a Pt/Ti/SiO2/Si substrate. The microstructure, surface morphology, dielectric and tunable properties of PST thin films were investigated as a function of Mg concentration. It is found that proper Mg doping dramatically improves the dielectric loss (0.0088 @ 1 MHz), furthermore, the crystallinity, dielectric constant, and tunability of films simultaneously decrease with the increase of Mg content. The 2 mol% Mg doped PST thin film shows the highest figure of merit (FOM) value of 36.8 for its the smallest dielectric loss and upper tunability. The dependence of Rayleigh coefficient on the doping concentration was examined, which indicated that the reduction of dielectric constant and tunability of films should be related to the \(\mathrm{Mg}''_{\mathrm{Ti}}\)–\(\mathrm{V}_{\mathrm{O}}^{\bullet\bullet}\) defect dipoles pinning the domain wall motion of residual polar clusters in PST.

Highlights

Solid solutions of Pbx Sr1−x TiO3 (PST) thin films have drawn great attention in recent years
In order to further improve the performance of PST films, many efforts have been tried in various ways
In PST system, though some researches [11, 12] about acceptor doping have been carried out, most of them mainly focus on the effect of acceptor dopant on the dielectric loss, and the related physics mechanisms behind the element doping adjusting defect concentration and types and changing polarization and dielectric properties still need to be explored

Summary

Introduction

Solid solutions of Pbx Sr1−x TiO3 (PST) thin films have drawn great attention in recent years. Its Curie temperature can be adjusted linearly from 490 to −230 ◦C with increasing Sr content and the process temperature of PST films is relatively low. It is considered as one of the most potential candidate materials for the future tunable microwave device components, such as phase shifters, filters, varactors, delay lines, etc. In PST system, though some researches [11, 12] about acceptor doping have been carried out, most of them mainly focus on the effect of acceptor dopant on the dielectric loss, and the related physics mechanisms behind the element doping adjusting defect concentration and types and changing polarization and dielectric properties still need to be explored. The Rayleigh law was used to characterize the effect of Mg as an acceptor dopant on the defects, polarization and dielectric properties of films

Experimental procedure

Results and discussion

Conclusion