Nossikpendou Sama

Analysis of size effects in Pb(Zr0.54Ti0.46)O3 thin film capacitors with platinum and LaNiO3 conducting oxide electrodes

The problem of thickness dependence of dielectric and ferroelectric properties of Pb(Zr0.54Ti0.46)O3 (PZT) thin film capacitors is addressed. Experimental data collected on PZT capacitors with different thicknesses and different electrode configurations, using platinum and LaNiO3 conducting oxide, are examined within the prism of existing models. Available literature data, abounding but contradictory, led us to conclude that in the range of thickness investigated, size effect under all its aspects, i.e., increase in coercive field (Ec) as well as decrease in both dielectric permittivity and remnant polarization (Pr), result basically from existence of a depolarization field. It is shown however that the latter arises from interface chemistry, mostly related to the upper surface of the films, instead of finite screening length in the electrodes unlike commonly accepted. Moreover it is established that increase in Ec and decrease in Pr are not concomitant, and significant degradation of one or the other of ...

Interface depolarization field as common denominator of fatigue and size effect in Pb(Zr0.54Ti0.46)O3 ferroelectric thin film capacitors

Dielectric, hysteresis and fatigue measurements are performed on Pb(Zr0.54Ti0.46)O3 (PZT) thin film capacitors with different thicknesses and different electrode configurations, using platinum and LaNiO3 conducting oxide. The data are compared with those collected in a previous work devoted to study of size effect by R. Bouregba et al., [J. Appl. Phys. 106, 044101 (2009)]. Deterioration of the ferroelectric properties, consecutive to fatigue cycling and thickness downscaling, presents very similar characteristics and allows drawing up a direct correlation between the two phenomena. Namely, interface depolarization field (Edep) resulting from interface chemistry is found to be the common denominator, fatigue phenomena is manifestation of strengthen of Edep in the course of time. Change in dielectric permittivity, in remnant and coercive values as well as in the shape of hysteresis loops are mediated by competition between degradation of dielectric properties of the interfaces and possible accumulation of i...

Low-temperature crystallization of high performance Pb0.4Sr0.6TiO3 films compatible with the current silicon-based microelectronic technology

This investigation presents a simple approach to realize the low temperature crystallization of Pb0.4Sr0.6TiO3 thin films at 400 °C by taking advantage of well controlled lead excess and kinetic-driving-force compensated thermodynamics crystalline via sputtering deposition. The thin films prepared at low temperature show fine-grained micro-structure because of the suppressed grain growth, furthermore, the intrinsic dielectric response can be modulated by the distinct level of crystallinity. The film processed at 450 °C exhibited a dielectric constant of 435 and high figure merit of 130 at 400 kV/cm, superior ferroelectric property, and stable performance with temperature and frequency.

Effect of interface configurations on the dynamic scaling behavior of Pb(Zr0.53Ti0.47)O3 thin films

The ferroelectric hysteresis and the scaling relations of hysteresis area ⟨A⟩ against field amplitude E and frequency f in Pb(Zr0.53Ti0.47)O3 thin films using platinum and LaNiO3 (LNO) as both bottom and top electrodes were systematically investigated. Interestingly, it was found that the influence of top electrodes is dominant in affecting the scaling behavior of the dynamic hysteresis, which may be the result of the asymmetric interface structure deriving from the differences in conductivity and crystallization of the top and bottom LNO electrodes. The bottom electrodes affect the scaling behavior slightly via influencing the micro-structural and level of space charge.