Ga ordering and electrical conductivity in nanotwin and superlattice-structured Ga-doped ZnO

We have investigated the Ga-ordering controlled by structural changes from nanotwin to superlattice in Ga-doped ZnO (GZO) targets for transparent conductive oxides (TCOs) and discussed the distribution effect of Ga atoms on electrical conductivities of GZOs. The nanotwin and superlattice structures were preferentially formed by Ga-doping and sintering at high temperature. The relative fraction of nanotwin increased above transition concentration (TC ≈ 5.6 wt % Ga). Here, we found that Ga atoms at nanotwin are distributed as clustered and disordered states, while they are completely ordered in superlattice. Ultimately, the superlattice leads to high electrical conductivity in GZOs rather than the nanotwin.