Interaction Between Na and Li in ZnO

Abstract

The interaction between group-Ia elements in ZnO have been studied by implanting Na into hydrothermally grown ZnO samples containing ∼4×1017 Li/cm3 and employing secondary ion mass spectrometry for sample analysis. Postimplantation annealing above 500 °C results in a diffusion of Na and concurrently Li is efficiently depleted from the regions occupied by Na. The data show unambiguously that Na and Li compete for the same trapping site and the results provide strong experimental evidence for that the formation energies of Na on Zn site together with that of interstitial Li are lower than those of Li on Zn site and interstitial Na in highly resistive ZnO. This conclusion is also supported by recent theoretical estimates of the formation energies of these species as a function of the Fermi-level position in ZnO.