Theoretical description of ferroelectric and pyroelectric hystereses in the disordered ferroelectric-semiconductor films

Abstract

Model for ferroelectric semiconductors thin films accounting for the space varying permittivity J. Appl. Phys. 97, 024104 (2005); 10.1063/1.1834728 Improved ferroelectric and pyroelectric properties in Mn-doped lead zirconate titanate thin films J. Appl. Phys. 94, 5228 (2003); 10.1063/1.1613370 Competition between ferroelectric and semiconductor properties in Pb ( Zr 0.65 Ti 0.35 ) O 3 thin films deposited by sol-gel J. Appl. Phys. 93, 4776 (2003); 10.1063/1.1562009Ferroelectric polarization in stretched piezo-and pyroelectric poly(vinylidene fluoride-hexafluoropropylene) copolymer filmsWe have modified the Landau-Khalatnikov approach and shown that both the polar lattice and the screened charged defects determine the response of disordered ferroelectric semiconductors. This system exhibits the spatially inhomogeneous switching under the external field while the Landau-Khalatnikov model describes homogeneous switching with the sharp pyroelectric coefficient peak near the thermodynamic coercive field value. Our model gives more realistic pyroelectric hysteresis loop shape without any peaks near the coercive field and describes both qualitatively and quantitatively typical Pb͑Zr, Ti͒O 3 and ͑Sr, Ba͒Nb 2 O 6 films pyroelectric hysteresis loops.

Pyroelectric response of inhomogeneous ferroelectric-semiconductor films

“…Earlier we proved [9][10][11][12][13] that the effect of random defect leads to the non-zero average values of δD 2 even atD = 0. This means that the sample is divided into polar regions with opposite polarization, i.e.…”

“…In this way we obtained six coupled equations for the average displacement D, its mean-square fluctuation δD 2 and correlation δD δρ S , pyroelectric coefficientγ = ∂D ∂ T , its deviation δγ = ∂ δD 2 ∂ T and correlation with charge defects density fluctuations δγ δρ S = ∂ δD δρ S ∂ T (see [13]):…”

“…The renormalization of coefficients αR ≡ α + (γ + kBT /4πne)d 2 and αRT ≡ αT + kB4πned 2 is connected with the contribution of correlation and screening effects [9,13].…”

Interface polarization coupling in piezoelectric-semiconductor ferroelectric heterostructures

“…[1][2][3][4][5][6][7][8][9][10][11] The ferroelectric constituent possesses switchable dielectric polarization. This polarization can be exploited for modification of the electronic and optical properties of a semiconductor heterostructure.…”