ELECTRONIC-STRUCTURE OF (IN,GA)AS-(GA,AL)AS STRAINED-LAYER QUANTUM-WELLS

We discuss the growth of epitaxial structures of (In,Ga)As on GaAs substrates, with elastic and plastic strain, and study the effect of the corresponding built-in strain on the photoluminescence of quantum wells inserted into such buffer layers. In addition, we examine the effect of built-in strain on the full electronic structure of strained-layer quantum wells. Reflectivity data taken at 2 K, where we could measure ground state type I, as well as excited type I and type II transitions, have revealed that a correct description of these heterostructures requires including the effect of the spin-orbit split-off states in the valence band physics as soon as the configuration of the electron-to-light-hole potential profiles switches from type II to type I. We anticipate that this effect should be included for the calculation of threshold cur-rents in quantum well lasers made from such heterostructures.