  The spontaneous and piezoelectric polarizations of III-nitrides considerably
affect the operation of various III-nitride-based devices. We report an ab
initio study of the spontaneous polarization (SP) and piezoelectric (PZ)
constants of the III-nitride binary and ternary alloys with the hexagonal
reference structure. These calculated polarization properties offer us a
profound principle for polarization engineering of nitride semiconductor
devices, based on which we propose a few heterojunctions which have nearly-zero
polarization effect at the junctions that can potentially enhance optical and
power device performances. The polarization doping effect was investigated as
well and by BAlN grading from AlN the polarization doping effect can be
doubled.
