Photocurrent and photoluminescence spectroscopy of InAsxP1-x/InP strained quantum wells grown by chemical beam epitaxy

We report on optical investigations carried out on InAsxP1-x/InP single and multi-quantum well structures with arsenic compositions of 0.35 < x < 0.54 and various well widths grown by chemical beam epitaxy. Sharp well-defined satellite peaks observed on X-ray diffraction patterns suggest good interface quality achieved by improving growth interruption sequences. In addition, the strained quantum wells exhibit intense and narrow luminescence peaks at low temperature. Doublet and multiplet luminescence lines are assigned to emission from well thicknesses fluctuating by one monolayer. The experimental well-resolved absorption peaks observed from photocurrent spectra are attributed to electron-heavy-hole and electron-light-hole fundamental excitonic transitions. Energies deduced from measurements are compared with calculations within the framework of the envelope-function formalism. The strain-induced coupling between the light hole and spin-orbit valence bands and the electron-effective mass modification along the quantification axis of the quantum well (QW) are considered. The strained band-offset ratio Q(C) is chosen as one adjustable parameter. An excellent agreement between measured and calculated light and heavy exciton splitting energy is achieved with a Q(C) value of 0.70 +/- 0.02 and using structural parameters determined from X-ray diffraction analysis. In addition, Q(C) appears to be independent of the arsenic composition in the present range. (C) 1998 Elsevier Science B.V. All rights reserved.