The current state-of-the-art CdZnTe-based HgCdTe IR detectors are seriously limited by their higher cost and smaller array format size due to the lower device yield and smaller wafer size available, which is fundamentally dominated by the lower crystal quality. In recent years, much attention has been devoted to developing “third generation” infrared detectors, which requires imaging focal plane arrays (FPAs) to be of higher pixel density, lower cost, larger array size, higher operation temperature, and multiband detection. However, this development presents serious challenges to HgCdTe materials grown on CdZnTe substrates. This book will introduce the theoretical knowledge and experimental techniques to suppress the generation of misfit dislocations, control the propagation of misfit dislocations, and reduce the misfit dislocations in the epitaxial layers. The epitaxial growth of HgCdTe detectors on Si, Ge, GaAs, and GaSb provides a test vehicle. Though the focus is on applications and developoments in third gen IR senors, thie approached being developed for these systems can be applied to other semiconductor materials and devices, so readers will benefit from this book by understanding the knowledge and techniques to achieve high quality semiconductors on lattice-mismatched substrates. As a result, it will have a wide readership, beyond those directly involved with IR detectors, as the knowledge and techniques introduced in this book can be generally applied.