Excitation-power dependence of the near-band-edge photoluminescence of ZnO inverse opals and nanocrystal films

The excitation-power dependence of the near-band-edge emission in ZnO inverse opals and nanocrystal films has been studied. The dependence of the photoluminescence intensity I on the excitation power L can be described by a power law, i.e., I∼L^α, where α is an exponent that is often used to identify the origin of the near-band-edge emission from semiconductors in previous models. However, in this work, it was found that the values of α show a strong variation between ZnO inverse opals and nanocrystal films. And our results show that the change of α is mainly caused by the laser heating effects. Therefore, the value of α could not be simply employed to unequivocally evaluate the origin of the near-band-edge emission in complex nanostructures.