1. DOS tail origin is considered there?

The origin of DOS tails is fluctuations in the QW composition. Let us consider a QW with of certain (mean!) composition. From the composition, we can calculate the energy gap, Eg, and determine edges of the valence and conduction bands, Ev and Ec (with an accuracy of a reference point). If we have no fluctutations, we have no electron states below Ec and no holes states above Ev. When we have a fluctuation with increase Indium content, the local position of the conductiion band is below Ec. Averaged, we have some density of electron states below Ec and density of hole states above Ev. We assume that they obey the following relations:

electrons: DOS(E-Ec) ~ exp(E), E<0,
holes DOS(E-Ev) ~ exp (-E), E>0



Compostion fluctuaction model does not consider "Blue shift" of light-emitting wavelength by band filling effect or the change of QCSE(Quantum Confined Stark Effect) by In rich region.
user knows.
Where, user would like to know if user can see "Stark shift"?

2.1 We do NOT consider effect of composition fluctuations on the emission spectrum.
2.2 One can see the "blue shift" of the emission peak with the current caused by both band filling effect and reduction of QCSE due to the screening.