Free-exciton emission from AlN (0001) surface was characterized by angle-dependent photoluminescence (PL) measurement. As the radiation direction was inclined from the surface normal (c -axis direction), the emission intensity increased. This is because the optical transition between the conduction band and the top valence band is mainly allowed for light with the electric field parallel to the c -axis direction of AlN (E∥c) and consequently the free-exciton emission is strongly polarized for E∥c. By analyzing the angle-dependent PL intensities, the polarization ratio was estimated to be 0.995. This high polarization ratio results from the large negative crystal-field splitting energy.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)