An energy offset (
) is used to align the valence band of
different materials. In this work GaN is chosen as the reference for
the III-V materials (
eV). The energies of the conduction and
valence band edges are calculated by
The most widely cited value for the valence band offset of InN/GaN is the one reported by Martin et al.  ( eV). It was however determined over a decade ago, and the recent reevaluation of the band structure have rendered it dated. Recent studies show a valence band offset between 0.58  and 0.62 eV . The band alignment is shown schematically in Fig. 4.9.
For alloys the offset energy is calculated by the following expression :
As an example, for AlGaN with =0.22 the valence-band-offset against GaN is 0.25 eV. Our setup provides a value of 0.225 eV for =0.2, which is in a good agreement with the experimentally determined offset of 0.25 eV  for the same composition.