An organic–inorganic hybrid semiconductor for flexible thin film transistors using molecular layer deposition

Abstract

Indium oxide and indicone hybrid films consisting of indium oxide and an organic aromatic linker are grown via molecular layer deposition (MLD) using bis(trimethylsilyl)amido-diethyl indium (INCA-1) as the indium precursor, hydrogen peroxide (H₂O₂) as the oxidant, and hydroquinone (HQ) as the organic precursor. The semiconducting indium oxide and indicone hybrid film is obtained at a growth temperature of 150 °C. The variations in optical properties, crystallinity, and chemical structures of indium oxide and hybrid films from 99 : 1 (indium oxide : indicone cycle ratio) to 39 : 1 are analyzed using various experimental techniques such as spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Furthermore, transparent and conducting organic–inorganic hybrid thin films are grown via applying supercycles of the atomic layer deposition (ALD) of indium oxide and MLD of indicone. The optical, structural, and electrical properties of the hybrid thin films can be adjusted according to the super-cycle ratio. In particular, the hybrid film with a 99 : 1 cycle ratio of indium oxide : indicone shows suitable TFT parameters with a field effect mobility of 2.05 cm² V⁻¹ s⁻¹, a threshold voltage of 2.22 V, a subthreshold swing of 0.53 V dec⁻¹, and excellent mechanical properties. Little change in electrical performance was measured even after repeated bending over 200 000 cycles with a 2 mm bending radius. The currently developed indicone-based hybrid thin film is expected to be applied in next-generation premium electronic devices.