Ferroelectric behavior in thin films of antiferroelectric materials

We show that when a typically antiferroelectric material such as PbZrO₃ or BiNbO₄ is deposited as a thin film on a semiconducting substrate (Si), it displays ferroelectric behavior below a critical film thickness characteristic of the system. In an attempt to understand this ``size effect,'' we consider the contributions of residual strain and the self-biasing effect produced by the intrinsic electric field at the semiconductor-insulator interface.