Spatially-resolved photoluminescence studies of V-shaped pits on $Al0.16Ga0.84N$

We have studied optical properties of V-shaped pits on $Al0.16Ga0.84N.$ The microphotoluminescence spectrum from the pit center shows a broader and stronger emission at 350 nm than the near-band-edge emission at 336 nm from nonpit regions. The results indicated specific defect levels associated with the V-shaped pits. Furthermore, after using atomic force microscopy to probe the surface electrical potential with a conductive tip, the pit’s potential was ∼0.2 V lower than its surrounding region. A simplified energy diagram is tentatively proposed to interpret our observation.