ZnO thin films with stable, tunable electrical and optical properties deposited by atomic layer deposition using Et2Zn:NEtMe2 precursor

ZnO thin films were deposited via atomic layer deposition (ALD), using Zn precursor, DEZDMEA (Et2Zn:NEtMe2) and H2O as a reactant. The design of DEZDMEA aimed to achieve enhanced stability and reduced decomposition compared to traditional DEZ (Et2Zn) precursor, as verified through NMR analysis, leading to the ZnO thin films with no-detectable impurities. The growth characteristics of ZnO thin films with the DEZDMEA were systematically evaluated, and high growth rate and the self-limiting reaction were observed. The comparable ZnO growth rate using DEZDMEA with those using DEZ was shown due to the selective removal of one Et and NEtMe2 ligands during the surface adsorption of DEZDMEA as established by DFT calculations. Additionally, increasing the precursor pulse and reducing the H2O pulse time resulted in decreased resistivity of the ZnO thin films, due to the modulation of n-type defects. This approach provided a consistent contour map for achieving stable, reproducible, and tailored resistivity depending on the DEZDMEA pulse time, and H2O pulse time with its vapor pressure. Moreover, the optical band gap could be modulated as well. The utilization of DEZDMEA is anticipated to be a robust and effective method in ALD for Zn-related deposition, promising substantial advantages for commercial applications.