We discuss physics of nonlinear screening of thin pyroelectric (or ferroelectric) films or grains in a semiconductor matrix. Such screening is different from a conventional screening of thick pyroelectric films. For thin films or small grains, the polarization dipole is screened by charges that are much smaller than the polarization charge, and the depletion region providing the screening charge might be much larger than the characteristic size of the pyroelectric. These results are important for the analysis and design of numerous devices involving pyroelectric-semiconductor systems. (C) 2003 Elsevier Ltd. All rights reserved.