  We demonstrate that GaN formed in a Nanowall Network (NwN) morphology can
overcome fundamental limitations in optoelectronic devices, and enable high
light extraction and effective Mg incorporation for efficient p-GaN. We report
the growth of Mg doped GaN Nanowall network (NwN) by plasma assisted molecular
beam epitaxy (PA-MBE) that is characterized by Photoluminescence (PL)
spectroscopy, Raman spectroscopy, high-resolution X-ray diffraction (HR-XRD),
X-ray photoelectron spectroscopy (XPS) and Secondary ion mass spectroscopy
(SIMS). We record a photo-luminescence enhancement ($ \approx $3.2 times) in
lightly doped GaN as compared to that of undoped NwN. Two distinct (and broad)
blue luminescence peaks appears at 2.95 and 2.7 eV for the heavily doped GaN
(Mg $>10^{20}$ atoms $cm^{-3}$), of which the 2.95 eV peak is sensitive to
annealing is observed. XPS and SIMS measurements estimate the incorporated Mg
concentration to be $10^{20}$ atoms $cm^{-3}$ in GaN NwN morphology, while
retaining its band edge emission at $\approx$ 3.4 eV. A higher Mg accumulation
towards the GaN/Al$_2$O$_3$ interface as compared to the surface was observed
from SIMS measurements.
