Energy offset between valence band anti-crossing and optical polarization switching in semipolar InGaN quantum wells

Abstract

Light emitted from a semipolar InGaN quantum well parallel to the surface normal is partially polarized, in contrast to the unpolarized emission of c-plane quantum wells. Anti-crossing of the two topmost valence bands causes polarization switching between ordinary and extraordinary polarizations for certain semipolar quantum well orientations with increasing indium content. Two properties of the two measured spectra, their polarization resolved but spectrally integrated intensity and their measured energy splitting, are associated with anti-crossing. Here, we show that only the observable energy splitting coincides with band anti-crossing, while the switching point of the polarization can deviate from the anti-crossing point.