  Density functional theory simulations were used to obtain physical properties
of GaN/AlN system. Combination of these two compounds into multiquantum well
(MQW) structure will induce strong electrostatic effect leading to emergence of
high magnitude dipole layers at the AlN/GaN interfaces, which were first
postulated by {Tersoff Phys. Rev. B 30(8) pp.4874 (1984)} and already
identified in GaN/InN by {Romanowski et al. J. Phys. Chem C 114. 14410 (2010)}.
When combining GaN and AlN in to a heterostructure a spatial projection of
wavefunctions indicate that valence band offset between states becomes of order
of 0.85 V. Systematic analysis of influence of number of Ga atomic layers on
the properties of wells have shown that for thickness up to 4 Ga layers, GaN
behave as carriers locating potential minimum rather, while for larger
thickness it is a standard quantum well. In all cases wells has strongly
localized quantum states close to valance band maxima (VBM) and conduction band
minimum (CBM). The calculated oscillator strength values rapidly decreases for
the well thickness in excess of 8 Ga layers (~21 {\AA}) which indicates that
wells for UV emitters should be much thinner than these based on InGaN/GaN
systems. The Quantum Confined Stark Effect (QCSE) related changes of the
transition energy in function of the geometric arrangement were also obtained.
