Published online by Cambridge University Press: 26 February 2011
The low-temperature (20K) photoluminescence of InxGa1-xAs and InxGal-xAs - GaAs strained-layer superlattices (SLS's) grown by molecular beam epitaxy (MBE) is investigated. Data are presented for thick (bulk) epitaxial layers grown directly on GaAs and for relatively-thin (˜600Å) InxGa1-xAs layers under biaxial compression. Data are also presented for two series of SLS's. In the two series of SLS's, the InxGa1-xAs layer thickness (Lz) is held constant while only the GaAs layer thickness (LB) is varied. The photoluminescence (PL) spectra of the crystals are useful in analyzing the effects of biaxial strain, carrier confinement, and barrier layer thicknesses in SLS's. Results are compared with calculations based upon a modified Kronig-Penney model which incorporates the appropriate deformation potentials for SLS analysis. This type of analysis, in agreement with experimental data, suggests that the electron-to-light-hole transition can be lower in energy than the electron-to-heavy-hole transition in SLS's, depending upon layer thickness and crystal composition.