Many kinds of heteroepitaxial technologies to improve the quality of III-V on Si are discussed. Surface cleaning and preparation for epitaxial growth, initial interfacial buffer layers between the substrate and the film, many kinds of intermediate layers such as strained layer super lattice (SLS) inserted in the films, low substrate temperature growth and thermal treatments during and after film growth are reviewed. Defect passivation and growth on the patterned substrates are also discussed. Among these methods, essential processes are proposed to evaluate their effectiveness for the defect reduction. (C) 2001 Elsevier Science B.V. All rights reserved.