Generally, the only way to make wavelength longer is to make QW wider or
make the energy gap narrower (i.e. increase In content). Also, there is
still some discussion about material parameters. Some authors recommend the
bandgap bowing parameter for InGaN to be 2.5 eV (instead of 1.2 eV by
default in SiLENSe). Increase of the bowing parameter will give a narrower
bandgap at the same In content.
