Ultrathin Vapor–Liquid–Solid Grown Titanium Dioxide-II Film on Bulk GaAs Substrates for Advanced Metal–Oxide–Semiconductor Device Applications

Abstract

In this paper, a high-quality crystalline thin film (~10 nm) of titanium dioxide (TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -II) phase is grown on p-GaAs (100) substrate by employing the vapor-liquid- solid method. The formation of crystalline TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -II films is confirmed by X-ray diffraction study. A very small rms surface roughness of ~1 nm has been measured from atomic force microscopy. The capacitance-voltage characteristics of Al/TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -II/GaAs metal-oxide-semiconductor (MOS) capacitor indicate the growth of excellent thin film of TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -II phase with high effective dielectric constant of 28, 35, 65, and 14 for the as-grown and 600 °C, 625 °C, and 650 °C annealed samples, respectively. An effective oxide thickness of ~0.7 nm, a negligible hysteresis of 10 mV, very small frequency dispersion of 3.5%, and a reduced gate leakage current of ~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-13</sup> A/μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at +2 V are achieved due to annealing in the temperature range of 600 °C-625 °C. Thus, this paper provides a cost-effective novel alternative technique to grow high-quality TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -II films on GaAs substrate which may be used as the reliable high-k gate dielectrics on III-V semiconductor-based MOS devices and circuits.