Barrier-width dependence of group-III nitrides quantum-well transition energies

Electrostatic effects which take place in group-m nitrides in their wurtzit e crystallographic phase have important consequences on the optical propert ies of (Al,Ga)N/GaN multiple quantum wells. A low-temperature photoluminesc ence study shows that the behavior of the transition energy versus the barr ier width is the opposite of that currently obtained for more usual m-V sem iconductor compounds like arsenides: when decreasing the barrier thickness, a blueshift is observed. This behavior is attributed to a redistribution a cross the samples of the huge built-in electric field (several hundreds kV/ cm) induced by the polarization difference between wells and barriers. The trend of the barrier-width dependence of the electric field is reproduced b y using simple electrostatic arguments. However, the field magnitude is hig her than that predicted laking account only piezoelectric effects. This res ult points out the role of the spontaneous polarization in wurtzite nitride s. [S0163-1829(99)13627-0].