Abstract
The author discusses the design and growth of relaxed buffer layers, where the objective is to achieve a single-crystal, defect-free surface with a lattice constant different from that of the substrate. From experimental results in the (InGa)As system, he suggests that the in-plane lattice constant should be changed in small steps, and that before each change in lattice constant the residual stress should be balanced by tensile layers so that the buffer layer is free from external stress. He anticipates that this prescription should be applicable to relaxed layers in the group IV, III-V and II-VI semiconductor systems.