Article pubs.acs.org/JPCC
Highly Conductive and Transparent Hybrid Organic−Inorganic Zincone Thin Films Using Atomic and Molecular Layer Deposition Byunghoon Yoon,†,§ Byoung H. Lee,† and Steven M. George*,†,‡,§ †
Department of Chemistry & Biochemistry and ‡Department of Chemical & Biological Engineering, University of Colorado at Boulder, Boulder, Colorado 80309, United States § DARPA Center for Integrated Micro/Nano-Electromechanical Transducers (iMINT), University of Colorado at Boulder, Boulder, Colorado 80309, United States ABSTRACT: Highly conducting and transparent hybrid organic− inorganic thin films were grown using atomic layer deposition (ALD) and molecular layer deposition (MLD) techniques. The conducting films were grown at 150 °C by combining ZnO ALD and zincone MLD processes. ZnO ALD was performed using diethylzinc (DEZ) and water (H2O). Zincone MLD was performed using DEZ and hydroquinone (HQ). The ALD:MLD alloys were deposited by controlling the relative number of ALD and MLD cycles in the reaction sequence. The growth of the ALD:MLD alloys was examined using in situ quartz crystal microbalance and Fourier transform infrared spectroscopy studies. The surface reactions during alloy growth were self-limiting, and the ALD and MLD reaction sequences produced linear growth rates. The alloys exhibited exceptional conductivity relative to ZnO ALD films grown at 150 °C. The highest conductivities were obtained from alloys with ALD:MLD cycle ratios of 1:1 and 2:2. The 1:1 and 2:2 alloy films yielded conductivities of 116 and 170 S/cm, respectively. In comparison, ZnO ALD films displayed a conductivity of 14 S/cm. The high conductivities for the zincone alloys may result from the modulated structure in the alloy that provides high charge carrier densities and high mobilities. The alloy films were also transparent and displayed high transmission until their band-gap absorption at
