Data are presented on the electroabsorption spectra of a single 10-nm GaAs quantum well bounded within Al0.2Ga0.8As under conditions for which the excitonic features are unresolved. Over an electric-field range of 100 500 kV/cm, the spectra are bounded by two- and three-dimensional electroabsorption limits. The three-dimensional limit occurs because of strong tunnel coupling to the continuum states, resulting in lifetime broadening of the transitions. Model studies using the one-electron-overlap-integral picture confirm this behavior and predict absorption coefficients and spectra in reasonable agreement with the data. Estimates of the high-field lifetime suggest that use of this mechanism for a practical modulator would reduce some of the intensity and recovery-time limitations of traditional exciton-based modulators.
ASJC Scopus subject areas
- Condensed Matter Physics