Structural properties of semipolar Al_xGa_(1_x)N(1103) films grown on ZnO substrates using room temperature epitaxial buffer layers

摘要

We have grown Al_xGa_(1-x)N films on semipolar ZnO (1103) substrates by pulsed laser deposition (PLD). The direct growth of Alo.25Gao.75N on ZnO (lT03) substrates at 850 ℃ results in the formation of c-axis oriented materials with poor crystal-linity due to serious interfacial reactions that occur between Alo.25Gao.75N and ZnO. However, epitaxial Al_xGa_(1-x)N (1103) films can be grown on ZnO substrates by the incorporation of PLD room temperature (RT) epitaxial buffer layers. From X- ray symmetric reciprocal space mapping studies, the [1103] directions of all AlxGa_(1-x)N (1103) layers are slightly tilted toward the c-axis from that of the ZnO substrate. We also found that the magnitude of the crystallographic tilt of Al_xGa_(1-x)N (1103) increases with A1N mole fraction x. This tendency can be explained by a reduction in the average misfit dislocation interval due to the increasing lattice mismatch between AlxGa_(1-x)N and ZnO with A1N mole fraction x.