Optical properties of edge dislocations on (11̄00) prismatic planes in wurtzite ZnO introduced at elevated temperatures

An arbitrary number (3 × 10 ⁸ - 1 × 10 ¹⁰ cm ^-2) of edge dislocations on (11̄00) prismatic planes, with the Burgers vector of (a/3) [112̄0] and with the dislocation lines nearly parallel to [0001], were introduced intentionally in wurtzite ZnO bulk single crystals at elevated temperatures of 923-1073 K, and the optical properties were examined. After the introduction of the dislocations, the intensity of the intrinsic emissions existing in pre-dislocated crystals, i.e., near-band edge emissions and deep level emissions, was almost unchanged, and donor-acceptor pair (DAP) emissions with photon energies of 2.20 and 2.50 eV at temperature of 12 K appeared. The intensity of the DAP emissions increased with increasing the dislocation density. The origin of the DAP emissions was determined as acceptor levels of 0.9 and 1.2 eV depth introduced with the dislocations.