Effect of working pressure and annealing temperature on microstructure and surface chemical composition of barium strontium titanate films grown by pulsed laser deposition

Bulletin of materials science

Seyed Mohammad Mahdavi¹  Ali Nemati²  Zahra Saroukhani²  Nemat Tahmasebi³ 

[1] Department of Physics, Sharif University of Technology, Tehran 11155â€�??9161, Iran$$Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran 11155â€�??9161, Iran$$Department of Physics, Sharif University of Technology, Tehran 11155â€�??9161, IranDepartment of Physics, Sharif University of Technology, Tehran 11155â€�??9161, Iran$$Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran 11155â€�??9161, Iran$$Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran 11155â€�??9161, IranDepartment of Physics, Sharif University of Technology, Tehran 11155â€�??9161, Iran$$Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran 11155â€�??9161, Iran$$;Department of Material Science and Engineering, Sharif University of Technology, Tehran 11155â€�??9161, Iran$$Department of Material Science and Engineering, Sharif University of Technology, Tehran 11155â€�??9161, IranDepartment of Material Science and Engineering, Sharif University of Technology, Tehran 11155â€�??9161, Iran$$;Department of Basic Science, Jundi-Shapur University of Technology, Dezful 64615â€�??334, Iran$$Department of Basic Science, Jundi-Shapur University of Technology, Dezful 64615â€�??334, IranDepartment of Basic Science, Jundi-Shapur University of Technology, Dezful 64615â€�??334, Iran$$

关键词: Barium strontium titanate;    thin film;    pulsed laser deposition;    ferroelectric.;   

DOI  :  

学科分类：材料工程

来源: Indian Academy of Sciences

【 摘 要 】

Barium strontium titanate (BST, Ba_{1−ð�?��?}Sr_ð‘�?TiO₃) thin films have been extensively used in many dielectric devices such as dynamic random access memories (DRAMs). To optimize its characteristics, a microstructural control is essential. In this paper, Ba_0.6Sr_0.4TiO₃ thin film has been deposited on the SiO₂/Si substrate by the pulsed laser deposition (PLD) technique at three different oxygen working pressures of 100, 220 and 350 mTorr. Then the deposited thin films at 100 mTorr oxygen pressure were annealed for 50 min in oxygen ambient at three different temperatures: 650, 720 and 800°C. The effect of oxygen working pressure during laser ablation and thermal treatment on the films was investigated by using X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) analysis methods. X-ray photoelectron spectroscopy analysis was used to determine the surface chemical composition of the samples. The results indicate that the deposited BST film at low working pressure (100 mTorr) in PLD chamber shows a lower surface roughness than other working pressures (220 and 350 mTorr). The as-deposited films show an amorphous structure and would turn into polycrystalline structure at annealing temperature above 650°C. Increase of temperature would cause the formation of cubic and per-ovskite phases, improvement in crystalline peaks and also result in the decomposition of BST at high temperature (above 800°C). In addition, rising of temperature leads to the increase in size of grains and clusters. Therefore more roughness was found at higher temperatures as a result of a more heterogeneous growth and less tensions.

【 授权许可】

Unknown