Atomic layer deposition of ZnO transparent conducting oxides

ZnO films have been successfully grown by atomic layer deposition (ALD) using diethylzinc (DEZn) and H2O as reactant gases. The processing window of self-limiting growth was observed for the substrate temperature range from 105 to 165°C. The films had a good uniformity in thickness due to the self-limiting feature of ALD. A high electron mobility of 30 cm2/V·s was obtained for undoped ZnO films with the thickness of only 220 nm. Furthermore, a resistivity of 7.5×10−4 Ω cm was achieved for the B-doped ZnO film at a B2H6 flow rate of 0.42 μmol/min. For further improvement of electrical properties, the effect of UV light irradiation during the ALD growth was examined and it was found that the resistivity of the films grown with UV irradiation (photo-ALD) was one order of magnitude less than that grown without UV irradiation.