High-Dielectric-Constant MgZrO₃ by Spray Pyrolysis for Thin-Fim Transistors in Low-Power Electronics

This study presents the synthesis and characterization of MgZrO3, a high-dielectric-constant (k) material tailored for nanocrystalline indium gallium zinc oxide (IGZO) thin-film transistors (TFTs). MgZrO3 films were deposited via spray pyrolysis at 400 °C, yielding a uniform amorphous structure with enhanced surface quality, as confirmed by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A 30 nm MgZrO3 film exhibited a high mass density of 5.76 g/cm3 and an RMS roughness of 0.29 nm, contributing to a low leakage current density (5.54 × 10–7 A/cm2) at 4 MV cm–1, a high dielectric constant (14.8), and a high breakdown electric field (5.16 MV cm–1) in a metal–insulator–metal (MIM) structure. X-ray photoelectron spectroscopy (XPS) depth analysis revealed a robust metal-oxide bond ratio (∼75%) at the MgZrO3/IGZO interface, with oxygen-related defects (∼25%), enhancing the electrical properties of MgZrO3/IGZO TFTs. The IGZO TFT demonstrated high field-effect mobility (20 cm2/V·s), small subthreshold swing (88 mV/dec), and high on/off current ratio (∼109), with zero hysteresis voltage and low gate leakage currents (∼10–13 A). In addition, IGZO TFTs with MgZrO3 dielectrics exhibited excellent bias stability under positive or negative bias stress and maintained their environmental stability over 90 days.