High doping efficiency Al-doped ZnO films prepared by co-injection spatial atomic layer deposition

Aluminum-doped ZnO (AZO) films are prepared by using spatial atomic layer deposition (ALD). The precursors of trimethylaluminum (TMA) and diethylzinc (DEZ) are concurrently introduced into the deposition region. The amount ratio of TMA to DEZ vapor molecules is controlled by varying the temperature of the precursor bubblers from 5° to 77 °C. It is found that the Al doping level can be predicted using the amount ratio of TMA to DEZ output vapors. The film prepared at the bubbler temperature of 41 °C exhibits an Al content of ~1% and a low resistivity of 3.5 × 10−4 Ω-cm comparable to indium tin oxide films. Furthermore, the Al-doping efficiency is as high as 73%. This study is useful in applying the ALD technique to films with multicomponent oxides.