Substrate temperature dependence of the phase transition behavior of AlN layers grown on Si(111) substrate by metalorganic chemical vapor deposition

The microstructural properties of AlN layers grown on a Si(1 1 1) substrate were studied in detail using transmission electron microscope techniques to determine phase transition behaviors. AlN layers were grown in the wurtzite (WZ) and zinc-blende (ZB) polytypes. The dominant phase of AlN was transformed from a ZB structure to a WZ structure as the substrate temperature increased. Many protrusions were observed on the surfaces of AlN layers, and their density was decreased with an increase in the substrate temperature; these protrusions originated from the WZ structure of AlN and not the ZB structure. In our experiment, WZ-AlN grains were frequently observed at the edge and/or on the surface of the ZB-AlN grains at relatively low substrate temperatures. The preferred crystallographic orientation relationships of the {111} ZB-AlN ‖{111} Si and ZB-AlN ‖ Si between the ZB-AlN and the Si substrate and the (0001) WZ–AlN ‖(111) Si and [1210] WZ-AlN //[11()0] Si between WZ-AlN and the Si substrate were identified in our experiment.