Slow oscillations in the low-temperature optical reflectance spectra of ZnO: Surface space-charge effect

Low-temperature optical reflectance spectra from (10 1- 0) surface of a ZnO crystalline rod were measured at near normal incidence. These spectra show slow oscillations which originate from the interference between lights reflected from the front surface and the second surface of a space-charge double layer formed on ZnO (10 1- 0). It is found that the oscillation period is linearly dependent on the wavelength of light. The expanding rate of the space-charge double layer is estimated to be 1.3 nmmin. © 2007 American Institute of Physics.published_or_final_versio