Photoluminescence spectroscopy of defects in ZnO nano/microwires

Photoluminescence spectroscopy is used to study defects found in single ZnO nano/microwires at 90 K. The defect, acting as binding site for bound exciton (BX) transition, is represented by B_F, the fractional intensity of the BX peak in the whole near-band edge ultraviolet (UV) luminescence. The concentration of defects as origins of the visible emissions is proportional to the intensity fraction D_F, i.e., the intensity fraction of visible emissions in the sum total of all UV and visible luminescences. By comparing B_F and D_F, it is concluded that the two defects are not correlated to each other. The former kind of defect is considered to be related to the blueshift of the near-band edge peak as the radius of the nano/microwires decreases at room temperature.