Stark shift of interband transitions in AlN∕GaN superlattices

The $e1h1$ , $e1h2$ , and $e1h3$ transitions of $\mathrm{Al}\mathrm{N}∕\mathrm{Ga}\mathrm{N}$ superlattices with different well widths were detected by electroreflectance measurements in dependence on the externally applied voltage. The quantum confined Stark effect of several tens of meV is observed, whose energy shift increases for larger well widths. The experimental results agree with quantum mechanical calculations at the Brillouin zone center. For well widths of 2.3 and $1.4\mathrm{nm}$ an intrinsic electric field strength in the wells of 5.04 and $6.07\mathrm{MV}∕\mathrm{cm}$ is calculated.