Article pubs.acs.org/JPCC
Growth Enhancement and Nitrogen Loss in ZnOxNy LowTemperature Atomic Layer Deposition with NH3 Soo Hyun Kim,† Jung Joon Pyeon,†,‡ Woo Chul Lee,†,§ Doo Seok Jeong,†,∥ Seung-Hyub Baek,†,∥ Jin-Sang Kim,† and Seong Keun Kim*,†,∥ †
Center for Electronic Materials, Korea Institute of Science and Technology, Seoul 02792, Korea KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea § Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Korea ∥ Department of Nanomaterials Science and Engineering, Korea University of Science and Technology, Daejeon 34113, Korea ‡
S Supporting Information *
ABSTRACT: The growth behavior and properties of ZnOxNy (ZnON) films grown by atomic layer deposition (ALD) with diethylzinc (DEZ), H2O, and NH3 were investigated. Although no growth of a ZnNx film occurs at 150 °C from DEZ and NH3, the ZnON film thickness is increasingly saturated by increasing ZnNx subcycles in a supercycle up to three successive ZnNx subcycles. The adsorbed NH3 during the injection step of NH3 induces the chemisorption of DEZ on the surface, consequently resulting in the growth enhancement. The optical band gap of the films decreases from 3.25 to 3.0 eV with increasing ZnNx subcycles. The resistivity of the films is tuned in the range from 4 × 10−2 to 1 × 102 Ω· cm by the variation of the ZnNx subcycles. However, the nitrogen concentration in the films is limited to approximately 2 at. % even at very high ZnNx cycles. The low nitrogen concentration is attributed to the exchange reaction of NH3 on the ZnON surface with H2O injected during the following step. These intriguing phenomena are not observed in the ALD of Al2OxNy with trimethylaluminum, which has a similar ligand structure as DEZ, H2O, and NH3. This finding demonstrates that the catalytic effect of NH3 adsorbed on the ZnO surface is critical for the growth enhancement in the ALD of ZnON. Al ions on the Al2O3 surface.22 Schuisky et al. reported successful growth of Bi2Ti2O7 films by ALD from Bi(C6H5)3, Ti[OCH(CH3)2]4, and H2O although no Bi2O3 was grown even from the same Bi and oxygen sources.23 In the ALD of some multicomponent materials, the difficult-to-grow component can be easily incorporated into the multicomponent films by the synergy between subcycles of each material. It is possible for oxynitride films to be grown by alternating oxide ALD cycles and nitride ALD cycles using NH3 even at low temperature (
