Interband optical transitions in the region of exciton resonances in In0.3Ga0.7As/GaAs quantum wells

Abstract

Reflectance spectra of quantum wells (QWs) with 8-nm-thick In0.3Ga0.7As layers with a 9-nm-thick GaAs barrier layer up and a 100-nm-thick barrier layer down were investigated in the spectral range of 0.5–1.6 eV in S- and P- polarizations at an incidence angle close to the normal (7о) as well as at a Brewster angle (76о). Narrow lines at 0.9021; 1.0161; 1.1302; 1.1973; and 1.2766 eV were observed in the reflectance and absorption spectra, which are due to hh,lh1-e1(1s), hh1,lh1-e2(1s), hh2,lh2 -e2(1s), and hh3,lh3,-e3(1s) transitions, as well as features due to quantum dotes (QDs) formed at the interface of nanolayers and the buffer. The contours of reflectance and absorption spectra are calculated with a single-oscillator, and many-oscillator models. The oscillator strength and the damping parameter are estimated for the optical transitions in QWs and QDs. The radiative life time of the exciton in a QW and a QD was found to be τо = (2Г0)-1 = 2x10-12 s.