Epitaxial growth of ZnO on (1 1 1) Si free of an amorphous interlayer

Single crystalline (0 0 0 1) ZnO films were grown by pulsed-laser deposition on (1 1 1) Si substrates containing thin Sc2O3 buffer layers (1 and 5 nm) which were prepared by molecular-beam epitaxy at 700 °C. Both x-ray diffraction and transmission electron microscopy reveal that the ZnO films grown at 240 and 400 °C are highly crystalline with good epitaxy. The commonly seen amorphous SiOx layer has been successfully eliminated from the interface between the ZnO/Sc2O3 film and (1 1 1) Si substrate, resulting in improved electrical properties. Rectifying effects are observed in the heterojunction exhibiting a turn-on voltage of 1.08 V and an ideality factor of 17.7. The room temperature mobility is 65 cm2 V−1 s−1. A donor binding energy of 46.7 meV is determined by temperature-dependent photoluminescence measurements. (paper)