Enhanced band edge luminescence from stress and defect free GaN nanowall network morphology

•We present a highly luminescent GaN nanostructured film grown by MBE.•Low stress and defect free material has been obtained.•Stress in various films is compared by XRD and correlated to luminescence.•Band structure is also drawn using values obtained by different measurements.

We report on very high brightness of high quality, dislocation free GaN nanowall network. The GaN nanowall network sample was grown by plasma assisted molecular beam epitaxy and the optical properties were investigated by photoluminescence (PL) and absorption spectroscopy. Other nanostructures and flat structures were grown for comparison and a standard epilayer was used as a reference sample. The PL intensity of the nanowall network structure was observed to be a hundred times more than nanostructures consisting of tubes, as well as flat films. To explain the broadness and the peak position values, strain was calculated by X-ray diffraction studies and a band diagram was proposed to elucidate the structure of these films using PL, absorption and XPS valence band values.