This book contains comprehensive reviews of different technologies to harness lattice mismatch in semiconductor heterostructures and their applications in electronic and optoelectronic devices. While the book is a bit focused on metamorphic epitaxial growth, it also includes other methods like compliant substrate, selective area growth, wafer bonding, heterostructure nanowires, and more. Basic knowledge on dislocations in semiconductors and innovative methods to eliminate threading dislocations are provided, and successful device applications are reviewed. It covers a variety of important semiconductor materials like SiGe, III-V including GaN and nano-wires; epitaxial methods like molecular beam epitaxy and metal organic vapor phase epitaxy; and devices like transistors and lasers etc.