Electrical properties of the silicon oxide/Si structure formed with perchloric acid at 203°C

Immersion of Si in perchloric acid (HClO4) at 203°C forms silicon dioxide (SiO2) layers with a low interface state density of 1.5×1010 cm2 eV−1 even without hydrogen treatment. The SiO2 thickness increases linearly with the immersion time, and a 25 nm-thick SiO2 layer is formed by the immersion for 400 min. The leakage current density for the as-prepared oxide layers is high, while after heat treatment at 900°C in nitrogen, it decreases to less than 10−9 A cm−2 at the gate bias of ±1 V. This decrease is attributable to the desorption of chlorine-containing species from the SiO2 layers.