Determination of Diffusion Coefficient of Copper in ZnO (001) Single Crystals at 1000 degrees C

Copper from a solid source was diffused into undoped n-type bulk ZnO (001) single crystals at 1000 degrees C under a nitrogen atmosphere at different diffusion times. The Cu diffusion profiles were obtained by Secondary ion mass spectroscopy (SIMS), and the fitting reveals a diffusion case from a constant concentration source. A value for the diffusion coefficient of 2.42(+/- 0.2) x 10(-12) cm(2)center dot s(-1) was obtained. Electrical measurements present an increment of carrier concentration with diffusion time, but remains n-type which indicates an increase in the donor levels produced by structural defects in ZnO. Photoluminescence (PL) spectra showed an increment of green emission intensity associated with Cu incorporation.