Browsing by Author "Shao, Jun"

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    Effective mass and valence-band structure in GaInAs/InP and GaInP/AlGaInP quantum wells
    (2002) Shao, Jun; Pilkuhn, M. H. (Prof. Dr.)
    In this dissertation main interests are focused on experimental and theoretical studies of exciton effects and on the valence-band structures in strained and/or ordered GaInAs/InP and GaInP/AlGaInP quantum well systems (QWs). Optical forbidden transitions are observed in the strained GaInAs/InP QWs by using magneto-optical absorption spectroscopy. The effective masses in the tensile strained GaInAs/InP QWs are for the first time reliably evaluated with spectroscopic derivative operations on the absorption spectra. With the determined effective masses the indirect valence-band structure in the tensile strained samples is evidenced, with an aid of a kp-simulation. In order to describe ordering effects in the GaInP/AlGaInP QWs, a modified model-solid method is established and the ordering effect on the effective masses is checked. Exciton transitions are investigated with reflectivity measurements to simultaneously determine the reduced effective masses for both the heavy-hole and light-hole subbands. The results show that (i) no diamagnetic shift is observable in the lattice-matched and disordered samples in a medium magnetic field, (ii) while for the compressively strained samples the diamagnetic shift is obvious and can be used to evaluate the reduced effective mass, (iii) the effective masses and exciton binding energies are ordering dependent. The ordering dependences of the effective masses and the valence-band structures are also analyzed using a modified 6-band kp model.