Compositional inhomogeneity of a high-efficiency InxGa1−xN based multiple quantum well ultraviolet emitter studied by three dimensional atom probe

An InxGa1−xN based multiple quantum well structure emitting in the ultraviolet, which has the highest reported efficiency (67%) at its wavelength (380nm), was analyzed with the three-dimensional atom probe. The results reveal gross discontinuities and compositional variations within the quantum well layers on a 20–100nm length scale. In addition, the analysis shows the presence of indium in the AlyGa1−yN barrier layers, albeit at a very low level. By comparing with analogous epilayer samples, we suggest that the quantum well discontinuities we observe may play an important role in improving the efficiency of these structures.