Ferroelectrics thin films

The requirements of thin-film ferroelectrics are stoichiometry, phase formation, crystallization, and microstmctural development for the various device appHcations. As of this writing multimagnetron sputtering (MMS) (56), multiion beam-reactive sputter (MIBERS) deposition (57), uv-excimer laser ablation (58), and electron cyclotron resonance (ECR) plasma-assisted growth (59) are the latest ferroelectric thin-film growth processes to satisfy the requirements. 

Ferroelectric thin films have not, as of this writing, been commercialized. Demand for PTC ferroelectrics has been decreasing rapidly. Wide usage of the fuel injector in automobiles and other types of composite PTC devices is the main reason. 

Ferroelectric Thin-Film Devices. Since 1989, the study of ferroelectric thin films has been an area of increasing growth. The compositions studied most extensively are in the PZT/PLZT family, although BaTiO, KNbO, and relaxor ferroelectric materials, such as PMN and PZN, have also been investigated. Solution deposition is the most frequentiy utilized fabrication process, because of the lower initial capital investment cost, ease of film fabrication, and the excellent dielectric and ferroelectric properties that result. 

Numerous uses for PZT/PLZT thin films are under investigation. The device that, as of this writing, is closest to commercialization is a nonvolatile memory. This device, which utilizes a ferroelectric thin-film capacitor integrated onto siUcon circuitry, provides memory retention when the power is off because of the polarization retention of the ferroelectric capacitor. One and zero memory states arise from the two polarization states, — and +F, of the ferroelectric. Because PZT is radiation-hard, the devices are also of interest for military and space appHcations. 

Sheppard, L., Advances in Processing of Ferroelectric Thin Films, CeramicBull, 71(l) 85-95 (1992)... 

Schneller, T. Waser, R. 2002. Chemical solution deposition of ferroelectric thin films—state of the art and recent trends. Ferro. 267 293-301. 

Waser, R. Schneller, T. Ehrhart, P. Hoffmann-Eifert, P. 2001. Chemical deposition methods for ferroelectric thin films. Ferro. 259(l-4) 205-214. 

Schwartz, R. W. Dobberstein, H. 2003. Modeling structural evolution in ferroelectric thin films. Proc. 11th US-Japan Seminar on Diet. Piezo. Ceram. (Sapporo, Japan), pp. 215-218. 

Kato, K. 1998. Low-temperature synthesis of SrBi2Ta209 ferroelectric thin films through the complex alkoxide method Effects of functional group, hydrolysis and water vapor treatment. Jpn. J. Appl. Phys. 37 5178-5184. 

Schwartz, R. W. Assink, R. A. Headley, T. J. 1992. Solution chemistry effects in PZT thin film processing spectroscopic and microstructural characterization. In Ferroelectric Thin Films II, edited by Kingon, A. I. Myers, E. R. Tuttle, B. Mat. Res. Soc. Symp. Proc. 243 245-254. 

Losego, M. D. Trolier-McKinstry, S. 2004. Mist deposition of micron thick lead zirconate titanate thick films. In Ferroelectric Thin Films XII, edited by Hoffmann-Eifert, S. Funakubo, H. Kingon, A. I. Koutsaroff, I. Joshi, V. Mat. Res. Soc. Symp. Proc. 784(C11.28) l-6. 

Haider, S. Schneller, T. Waser, R. Thomas, F. 2007. Microstructure and electrical properties of BaTi03 and (Ba,Sr)Ti03 ferroelectric thin films on nickel electrodes. /. Sol-Gel Sci. Tech. 42 203-207. 

In Table 1 we compare performance data for reported MRAM and FRAM prototypes. The small Fujitsu FRAM is not a prototype it is in large-scale production and found in the memory board of every Sony Playstation 2, as part of the Toshiba memory system. The main advantages of FRAMs over EEP-ROMs or Elash memory are in the WRITE times (100 ns for FRAM, versus 1 xs for Flash and 10 xs for EEPROM), and energy per 32-bit WRITE (1 nj for ERAM versus 1 or 2 mj for EEPROM or Plash). Note that parameters such as READ time or WRITE time for PRAMs are dependent upon actual cell architecture they are not limited by the intrinsic switching time of the ferroelectric thin film, which is typically 220 ps [3]. 

Funakubo H (2004) Recent development in the preparation of ferroelectric thin films by MOCVD. Ferroelectric Random Access Memories Fundamentals and Applications 93,95-103... 

Dey S.K in Ferroelectric Thin Films Synthesis and Basic Properties, ed C.P. Araujo, J.F. Scott, G.W. Taylor, Gordon Breach Publ., 1996. 

Based on these assumptions the measurement of the large signal ferroelectric hysteresis with additional measurements of the small signal capacitance at different bias voltages are interpreted in terms of reversible and irreversible parts of the polarization. As shown for ferroelectric thin films in Figure 1.24, the separation is done by substracting from the total polarization the reversible part, i. e. the integrated C(V)-curve [18]. 

Analogous C(V) curves were recorded on pzt bulk ceramics with compositions around the morphotropic phase boundary (mpb). Figure 1.25 displays the relative permittivity as a function of DC-bias for a tetragonal (x = 0.48), a morphotropic (x = 0.52) and a rhombohedral (.x = 0.58) sample. In contrast to thin films additional humps observed in the e E) curves. This could be explained by different coercive fields for 180° and non-180° domains [31]. Their absence in ferroelectric thin films could be taken as evidence for suppressed non-180° domain switching in thin films [30],... 

M. Grossmann, Imprint An Important Failure Mechanism of Ferroelectric Thin Films in View of Memory Applications. Dissertation. RWTH-Aachen, 2001. published by vdi Verlag, Fortschritt-Berichte vdi Reihe 9 Elektronik/Mikro- und Nanotechnik. 

A. Prokhorov, Yu Kuzminov, O. Khachaturyan, Ferroelectric Thin Film Waveguides in Integrated Optics, Cambridge International Science Publ., 1996. 

In this study, two methods of xrd-rsms and gixrd were applied to ferroelectric thin film. Which xrd-rsm is chosen depends on the orientation of the thin film media. In the following session, details of these two xrd-rsms and the gixrd and the comparison of them to the conventional 20 — 0 scan method are discussed. 

In-Situ Synchrotron X-ray Studies of Processing and Physics of Ferroelectric Thin Films... 

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