The microstructure of Er MBE doped GaN

For a few years now, it has been possible to dope GaN layers using molecular beam epitaxy (MBE) growth. This aims to use the wide band gap semiconductors as hosts to rare earth ions and exploit the sharp emission lines from atomic shell transitions. It was shown that the whole visible spectrum can be covered by addressing different exited states of various rare earth ions. It is also suspected that as in some systems like Si(nano)/SiO2, the energy coupling could involve defects. In this work, we carry out TEM and HREM analysis on MBE doped GaN layers grown on metal organic chemical vapour deposition (MOCVD) GaN templates. Er concentrations of 1, 6, and 16 at.% were subsequently measured by wavelength dispersive X-ray (WDX) in an electron probe. We discuss the results on the spatial distribution of the rare earth atoms at a nanometer scale.