Structural characterization of Eu-doped GaN by transmission electron microscopy

The structural properties of Eu-doped GaN films grown on sapphire (0001) substrates by molecular beam epitaxy were studied using cross sectional transmission electron microscopy (TEM). The Eu concentration was estimated to be about 2at.% by Rutherford backscattering spectrometry and energy dispersive X-ray spectroscopy. Selected area diffraction patterns of the film showed a hexagonal structure, and no other anomalous patterns such as from Eu and EuN were observed. The high resolution TEM observation of the films showed a high density of stacking faults which was hardly observed in undoped GaN, bending layers and a small portion of cubic phase. The causes of the formation of stacking faults and bending of layers are discussed.