Air-stable alucone thin films deposited by molecular layer deposition using a 4-mercaptophenol organic reactant

Abstract

Molecular layer deposition (MLD) is a thin film technique to make a pure organic coating or hybrid organic–inorganic film, sequentially dosing organic–organic or organic–inorganic precursors, respectively. In this study, hybrid organic–inorganic alucone films were fabricated via MLD using 4-mercaptophenol and trimethylaluminum as organic and metal precursors, respectively, over the deposition temperature range of 100–200 °C. The fabricated film was very stable without degradation when exposed to the atmosphere, and the characteristic change was confirmed through annealing under vacuum at 300–750 °C. After annealing, the thickness of the alucone films decreased and the bonding of the carbon ring changed, as revealed by the spectroscopic ellipsometer, Fourier-transform infrared, Raman, x-ray diffraction, and x-ray photoelectron spectroscopy results. The annealed alucone films showed thermal polymerization, and their carbon ring structures transformed into graphitic carbon flakes. The alucone film annealed at 750 °C showed an electrical resistivity of 0.55 Ω cm. Annealed MLD alucone films, which are hybrid materials, are potential candidates for applications in electronic, capacitor, and thermoelectric devices.