Dependence of electrical properties on film thickness in Pb(ZrxTi1−x)O3 thin films produced by metalorganic chemical vapor deposition

Abstract

Strongly c-axis oriented Pb(ZrxTi1−x)O3 (PZT) thin films with tetragonal perovskite structure (0.45≤x≤0.52) were epitaxially grown on (100)Pt/(100)MgO substrates using metalorganic chemical vapor deposition. Film thickness could be varied by altering the growth time. The electrical properties of PZT thin films sharply change below a thickness of 0.5 μm: the dielectric constant and remanent polarization decrease while the coercive field increases. These phenomena are explained by a model in which a layer with low dielectric constant exists in series with the normal PZT layer. The origins of this layer are systematically studied and found to be the intrinsic stress produced by the coalescence of crystal grains.

Size effects of 0.8SrBi2Ta2O9–0.2Bi3TiNbO9 thin films

“…This results are contrary to the reports of piezoelectric ͑PZT͒ films, where the electrical properties of PZT films strongly depend on thickness in the thickness range from 25 to 300 nm. [6][7][8]11,12 The films with thickness of 50-500 nm showed similar AFM microstructure. Figure 2 shows the AFM microstructure of the 80 nm film.…”

“…The low dielectric constant interfacial layers results in a decrease in the effective dielectric constant and remanent polarization, and increase in loss tangent and coercive field of the entire film. [12][13][14] The other model is based on the domain structure transition from multidomain predominance to single domain predominance at a critical grain size in the thin film. 19 The lack of the domain walls and the low domain wall mobility in the single domain predominated film, usually associated with small grains, may induce the size effects.…”

“…It has been found that the thickness and grain size of the thin film strongly effect the ferroelectric and optical properties, phase transitions, lattice structure, and stress distribution in ABO 3 type materials. [6][7][8][9][10][11][12][13][14][15][16][17][18] Generally speaking, a reduction in film thickness or grain size leads to a decrease in dielectric constant, remanent polarization, dielectric breakdown field, and the tetragonal distortion c/a, and leads to an increase in loss tangent, coercive field, band-gap energy, and diffuseness of the phase transitions. 7,10 Several mechanisms for size effects in ferroelectric thin films have been postulated based on the effects of electrodes/ film interfacial layers, 12-14 stresses, 17 defects, 18 and domain structure transitions.…”

“…One is the electrodes/film interfacial layers model. [12][13][14] The model assumes that an electrodes/film interfacial layers with low dielectric constant is formed at the interface between the electrode and ferroelectric film by the intrinsic stress during the synthesis process of the film. The low dielectric constant interfacial layers results in a decrease in the effective dielectric constant and remanent polarization, and increase in loss tangent and coercive field of the entire film.…”

Dependence of crystalline, ferroelectric and fracture toughness on annealing in Pb(Zr0.52Ti0.48)O3 thin films deposited by metal organic decomposition

“…MOD is one of the considerable deposition methods, since it is a non-gelling chemical process in which molecular homogeneity is attained in the liquid phase, and the solutions can be produced without solution gelling and at a lower processing temperature 5 . Few reports have shown that the microstructural charactheristics and electrical properties of PZT thin films depend greatly on the annealing temperature 8 and film thickness [9][10][11] , however little has been done in regard to the dependence of ferroelectric properties and fracture toughness on annealing procedure. It is known that ferroelectric and mechanical properties of thin film including remanent polarization, coercive field, fracture toughness, residual stress and hardness are very important parameters, which will be used to the design of the film/substrate system.…”