Reduction of dislocation density and improvement of optical quality in ZnO layers by MgO-buffer annealing

Optical properties of ZnO thin lms with/without MgO-buer annealing were investigated by low and room temperature photoluminescence measurements. The ZnO lms were grown onc-sapphire substrates by plasma-assisted molecular-beam epitaxy employing a thin MgO-buer layer. Dislocation density of ZnO layer was reduced from 5.3· 109 to 1.9· 109 cm. 2 by annealingMgO-buer prior to the growth of ZnO. The intensity of free exciton emission from the sample with MgO-buer annealing wasalmost twice of that from the sample without annealing, while the deep level emission from the sample with MgO-buer annealingwas about 1/3 of that without annealing. The MgO-buer annealing improves optical quality of overgrown ZnO lms. KCI Citation Count: 4