Calculations for the band lineup and band offsets of AlGaN/GaN Qws and effects of electric field on the photoluminescence

Band lineup is one of the most important parameters associated with carrier confinement in heterostructures. Relations for computing the band line-ups of Al_xGa_1-xN based heterostructures have been developed. The band positions for Al_xGa_1-xN/GaN heterointerfaces are calculated from the equations developed, which directly co-relate the positions of the bands with the strain at the interface. The strains are calculated from the Al mole fractions and lattice constants. The parameters implicitly involved are the elastic stiffness constants (C₁₁ and C₁₂), the hydrostatic deformation potential of the conduction band (a), the hydrostatic deformation potential (a) and shear deformation potential (b) for the valance band. AlGaN /GaN heterostructures are associated with strong piezoelectric fields of the order of Mv/cm. This field depends on the interfacial strain, which in turn depends on the composition. The effects of piezoelectric (PZ) field on the photoluminescence (PL) have been calculated through quantum mechanical (QM) computations.