Issue 5, 2021

Optimized Al-doped TiO2 gate insulator for a metal-oxide-semiconductor capacitor on a Ge substrate

Abstract

Atomic layer deposited TiO2- and Al2O3-based high-k gate insulators (GIs) were examined for the Ge-based metal-oxide-semiconductor field effective transistor (MOSFET) application. The single-layer TiO2 film showed a too high leakage current to be used as a useful GI. Interposing a thin Al2O3 layer at the TiO2/Ge interface was very effective in decreasing the leakage current. However, the resulting Al2O3/TiO2 interface induced various adverse charge effects, including the density of the slow trapping sites, fixed dipole charge, while the Al2O3/Ge interface had a low density of fast carrier trapping sites, especially after the forming gas annealing (FGA) at 400 °C. Therefore, the Al2O3/TiO2 stacked-layer could not be a viable GI on the Ge-substrate. In contrast, the Al-doped TiO2 (ATO) film showed highly promising performance as the GI on the Ge-substrate. The 5.8-nm-thick ATO film resulted in an equivalent oxide thickness of 1.24 nm and leakage current density of 3.2 × 10−2 A cm−2 at a flat band voltage of −1 V, which was lower than that of the TiO2 film by ∼three orders of magnitude. The slow trap density, fixed charge density, and interface trap density values of the ATO/Ge structure after the FGA were ∼1 × 1012 cm−2, ∼1.9 × 1011 cm−2, and ∼5 × 1011 cm−2 eV−1, respectively. The k value of the ATO was ∼27.

Graphical abstract: Optimized Al-doped TiO2 gate insulator for a metal-oxide-semiconductor capacitor on a Ge substrate

Supplementary files

Article information

Article type
Paper
Submitted
06 Oct 2020
Accepted
03 Jan 2021
First published
04 Jan 2021

J. Mater. Chem. C, 2021,9, 1572-1583

Optimized Al-doped TiO2 gate insulator for a metal-oxide-semiconductor capacitor on a Ge substrate

D. G. Kim, C. H. An, S. H. Kim, D. S. Kwon, J. Lim, W. Jeon and C. S. Hwang, J. Mater. Chem. C, 2021, 9, 1572 DOI: 10.1039/D0TC04725B

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements