Photoluminescence spectroscopy of defects in ZnO nano/microwires

Photoluminescence spectroscopy is used to study defects found in single ZnO nano/microwires at 90K. The defect, acting as binding site for bound exciton （BX） transition, is represented by BF, 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 DF, i.e., the intensity fraction of visible emissions in the sum total of all UV and visible luminescences. By comparing BF and DF, 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.