Structural, electrical, and optical characteristics of lithium-implanted ZnO thin films

Lithium ions were implanted at low energies (40 and 50 keV) and at a dosage of 5 × 1013 ions/cm2 over 〈0 0 2〉 ZnO thin films that had been deposited by pulsed laser deposition. The implanted samples were subsequently treated by rapid thermal annealing at 750 °C. Scanning electron microscopy images revealed improved grain formation for the implanted samples. However, a presence of microvoids was also observed in these samples; the amount of microvoids tended to increase on high-temperature annealing. Dominant donor-bound-exciton peaks is observed in all the samples along with some defect related to the exciton bound peaks although with a lesser intensity compared to as-deposited sample.

► Lithium-implantation performed on ZnO films to try to achieve p-type doping.
► Increase in carrier concentration for the implanted samples.
► Dominant donor-bound exciton peak for the samples, depict n-type conductivity.
► Presence of exciton bound defect peak due to implantation.
► No acceptor peak was visible in the PL spectra.