Energy band structure of CdS/CdSe intrinsic Stark superlattices

In strained-layer superlattices grown in appropriate crystallographic directions there exist large piezoelectric fields that affect the electronic band structure considerably. One of the first, and most striking, examples of these so-called intrinsic Stark superlattices was CdS/CdSe; this system has wurtzite form with the c axis normal to the plane of the (111)A GaAs substrate and the piezoelectric fields are calculated to be of order 10⁸ V m^-1. In the present paper, the authors analyse the properties of the charge carriers in such superlattices by using an envelope function approach with Airy functions Al(z) and Bi(z) as the basis solutions. This yields the exact wavefunctions and enables them to calculate the band structure as a function of the superlattice period.