TEM observation of Eu-doped GaN and fabrication of n-GaN/Eu:GaN/p-GaN structure

Structural properties of Eu-doped GaN with the Eu concentration of about 2 at% were studied by cross sectional transmission electron microscope (TEM) observation, and electrical and optical properties of n-GaN/Eu-doped GaN/p-GaN structure were discussed. Selected area diffraction pattern from Eu-doped GaN showed hexagonal structure and no other anomalous pattern was observed. These results suggest that the segregation of Eu and EuN were not formed. From the high resolution TEM observation of Eu-doped GaN, in addition to a small portion of cubic phase of GaN, high density of stacking irregularity which was hardly observed in undoped GaN was detected. Heterostructure of n-GaN/Eu:GaN/p-GaN was grown by molecular beam epitaxy on the p-type GaN template which was prepared by metalorganic chemical vapor deposition. Although the rectification behavior was observed, the electroluminescence was obtained not from the Eu-doped layer but from p-GaN layer. These results suggest that the hole mobility in Eu-doped GaN is extremely low probably due to the high density of stacking irregularity.