Tight-binding study of the optical properties of GaN/AlN polar and nonpolar quantum wells

The electronic structure of wurtzite semiconductor superlattices (SLs) and quantum wells (QWs) is calculated by using the empirical tight-binding method. The basis used consists of four orbitals per atom (sp model), and the calculations include the spin-orbit coupling as well as the strain and electric polarization effects. We focus our study on GaN/AlN quantum wells grown both in polar (C) and nonpolar (A) directions. The band structure, wave functions and optical absorption spectrum are obtained and compared for both cases.