Tuning the Oxygen Content in the Nb2O5 Thin Films Deposited on Si by DC Magnetron Sputtering for Energy Storage Devices Applications

Abstract

Nb 2 O 5 thin films were deposited on silicon substrate using DC magnetron sputtering by applying variable deposition power on a Nb target and fixing the oxygen flow rate during the deposition process. This technique helped the control of thin film thickness and oxygen-to-metal ratio. Successive deposition powers between 200 W up to 300 W were applied. The minimum thin film thickness was about 25 nm, and the corresponding energy band gap was 3.59 eV. The thin films showed high transmittance and refractive index in the visible region. These characteristics match the high-k materials requirements as replacement of SiO 2 layer in energy storage devices and DRAM applications. Keywords High-K materials, Energy storage devices, Metal oxides problem of tunneling current is to replace the SiO 2 thin film with a thicker layer of a high-k material, or (high-k metal oxide). The main essential requirement for the replacement metal oxide is that the k value should be more than 12 and the metal oxide should have a wide energy bandgap. Though, it has been noticed that the k value behaves inversely with the energy bandgap of the metal oxide [3]. The requirements of the replacement high-k metal oxides should be stated herein; the oxide should be thermodynamically stable, and in order to minimize carrier injection into metal oxide band it should have band offset with silicon over 1 eV. Additionally , it must have fewer electrically-active defects [3,4]. There are various oxides of considerable k-value but with a relatively small energy bandgap, such as