Optical absorption in semiconductor quantum dots: A tight-binding approach

We present a tight-binding calculation of the interband optical transitions in semiconductor quantum dots (QD's). The calculated optical-absorption spectra are in good agreement with the existing experimental spectra of CdS and CdSe QD's. We establish a correspondence between the tight-binding (TB) energy levels and those calculated using the spherical multiband effective-mass approximation (EMA). Consequently, the comparatively stringent selection rules of the latter are applicable to a large extent. Thus we formulate a convenient and quantitatively accurate description of the optical absorption in QD's in terms of the TB energy levels and multiband EMA quantum numbers.