Electro-optic effects in GaAs/AlGaAs parabolic quantum well structures

• Published in: Superlattices and microstructures 1998-01, Vol.23 (1), p.93-96
• Main Authors: Geisselbrecht, W., Masten, A., Gräbner, O., Forkel, M., Döhler, G.H., Campman, K., Gossard, A.C.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electrooptical effects; Exact sciences and technology; Iii-v semiconductors; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Optical properties of specific thin films; Physics
• ISSN: 0749-6036; 1096-3677
• DOI: 10.1006/spmi.1996.0312

We report on a systematic experimental and theoretical investigation of the interband electroabsorption in GaAs/AlGaAs parabolic quantum well (PQW) structures. In our experiments, we performed transmission and reflectance measurements using a sensitive double modulation technique. The measurements were carried out on p–i–n diode type PQW samples with two different well widths. In the sample with the narrow PQW, the discrete structure of the interband subband transitions can be resolved in the electroabsorption spectra. In the sample with the wide PQW, and therefore a small subband spacing, these transitions can no longer be resolved individually due to the broadening. Their superposition, however, results in a red-shifting, quasi-linear pattern in the electroabsorption spectra, which is modulated by the blue-shifting, non-linear fan of the ‘ arabolic Franz–Keldysh effect’. The experimental results are in very good agreement with calculated single-particle absorption spectra based on a simple harmonic oscillator model.