AVS 50th International Symposium
    Semiconductors Tuesday Sessions
       Session SC-TuM

Paper SC-TuM7
Electronic and Optical Properties of GaAsN/GaAs Quantum Wells

Tuesday, November 4, 2003, 10:20 am, Room 321/322

Session: Narrow Gap Semiconductors
Presenter: N. Shtinkov, École Polytechnique de Montréal, Canada
Authors: N. Shtinkov, École Polytechnique de Montréal, Canada
S. Turcotte, École Polytechnique de Montréal, Canada
J.-N. Beaudry, École Polytechnique de Montréal, Canada
P. Desjardins, École Polytechnique de Montréal, Canada
R.A. Masut, École Polytechnique de Montréal, Canada
G. Bentoumi, Université de Montréal, Canada
R. Leonelli, Université de Montréal, Canada
Correspondent: Click to Email
We present a theoretical and experimental investigation of the electronic structure and optical properties of GaAs@sub 1-x@N@sub x@/GaAs (001) quantum wells (QWs) with x < 0.045. The electronic structure is calculated using a recently developed empirical tight-binding (ETB) model, taking strain into account, for values of the GaN/GaAs valence band offset (VBO) from -4 to 4 eV. The valence band structure is found to be strongly influenced by the VBO and the strain-induced heavy hole-light hole splitting. At zero VBO only one heavy-hole and one light-hole state are observed. For VBO < 0 the ground hole state is localized in the barrier, but quasi-bound QW-localized heavy-hole states are observed in the continuum. For VBO > 0, the ground state is always a light-hole state localized in the QW, but there exist a number of excited heavy- and light-hole states. In spite of the significant influence of the VBO on the valence band structure, our results show that its effect on the transition energies is rather small for positive VBO. For example, changing the VBO from 0 to 4 eV in a QW with x = 0.04 shifts the ground state transition energy by only 16 meV. Therefore in simple rectangular QWs only the sign but not the value of the VBO can be unambiguously deduced from measurements of the transition energies. In order to compare our predictions with experimental results, we have measured low-temperature optical absorption spectra from fully coherent 7-period 7-nm-GaAs@sub 1-x@N@sub x@/15-nm-GaAs multiple quantum wells with x up to 0.04. We found that the measured ground-state and excited-state transitions are in good agreement with our ETB calculations when considering a positive GaAsN/GaAs VBO.