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Electrical, optical, structural and chemical properties of Al2TiO5 films for high-kappa gate dielectric applications

Addepalli, Suresh and Kolla, Lakshmi Ganapathi and Suda, Uthanna (2017) Electrical, optical, structural and chemical properties of Al2TiO5 films for high-kappa gate dielectric applications. In: MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING, 57 . pp. 137-146.

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Official URL: http://dx.doi.org/10.1016/j.mssp.2016.10.019

Abstract

In search of alternate gate dielectrics for electronic applications, aluminum titanate (Al2TiO5) thin films were deposited at room temperature by DC reactive magnetron sputtering and characterized for their structural, chemical, optical and dielectric properties. To realize the potentiality of these films for gate dielectric applications, we investigated the influence of annealing temperature on these properties. From X-ray photoelectron spectroscopic studies, it has been observed in the as-deposited films that the presence of Al3+ and Ti4+ oxidation states which correspond to Al2O3 and TiO2 respectively. After annealing at 400 degrees C in oxygen ambient, the binding energies of Al 2p, Ti 2p and O 1s were shifted by similar to 1 eV and it remains constant with further increase of annealing temperature from 400 to 800 degrees C. This indicates the formation of an intermediate compound of Al2O3 and TiO2. The extracted Al, Ti and O ratio was 2:1:5 which confirms the formation of Al2TiO5. XRD studies indicate that the as-deposited films were amorphous. After annealing at 400 degrees C, a diffraction peak (200) corresponds to aluminum titanate (Al2TiO5) started appearing, and its intensity increases with increase of annealing temperature. Metal-Oxide-Semiconductor (MOS) capacitors were fabricated and characterized to estimate the dielectric properties of the films. The as-deposited films shows high dielectric constant (kappa = 27.0 at 100 kHz) and high leakage current density values (J= 0.33 A/cm(2) at 1 MV/cm), high oxide traps (5.5x10(13) cm(-2)) and high interface state density (1.5x10(13) cm(-2) eV(-1)). After annealing the films show improved dielectric constant and leakage current density values. The films annealed at 600 degrees C in oxygen ambient show better dielectric constant (kappa = 11.2 at 100 kHz) and leakage current density values (J= 2.23x10(-9) A/cm(2) at 1 MV/cm), low oxide traps (1.4x10(12) cm(-2)) and low interface state density (7.1x10(11) cm(-2) eV(-1)) compared with the other films. This suggests that the optimum annealing temperature is required to achieve better device properties.

Item Type: Journal Article
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Additional Information: Copy right for this article belongs to the ELSEVIER SCI LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND
Department/Centre: Other Centres/Units/UG Programme > Centre for Nano Science and Engineering
Date Deposited: 30 Dec 2016 05:56
Last Modified: 30 Dec 2016 05:56
URI: http://eprints.iisc.ernet.in/id/eprint/55593

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