Effective Schottky Barrier Height Lowering of Metal/n-Ge with a TiO2/GeO2 Interlayer Stack
- Authors
- Kim, Gwang-Sik; Kim, Sun-Woo; Kim, Seung-Hwan; Park, June; Seo, Yujin; Cho, Byung Jin; Shin, Changhwan; Shim, Joon Hyung; Yu, Hyun-Yong
- Issue Date
- 28-12월-2016
- Publisher
- AMER CHEMICAL SOC
- Keywords
- germanium; Fermi-level unpinning; Schottky barrier height; contact resistance; plasma oxidation; germanium dioxide; titanium dioxide
- Citation
- ACS APPLIED MATERIALS & INTERFACES, v.8, no.51, pp.35419 - 35425
- Indexed
- SCIE
SCOPUS
- Journal Title
- ACS APPLIED MATERIALS & INTERFACES
- Volume
- 8
- Number
- 51
- Start Page
- 35419
- End Page
- 35425
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/86495
- DOI
- 10.1021/acsami.6b10947
- ISSN
- 1944-8244
- Abstract
- A perfect ohmic contact formation technique for low-resistance source/drain (S/D) contact of germanium (Ge) n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) is developed. A metal interlayer semiconductor (M-I-S) structure with an ultrathin TiO2/GeO2 interlayer stack is introduced into the contact scheme to alleviate Fermi-level pinning (FLP), and reduce the electron Schottky barrier height (SBH). The TiO2 interlayer can alleviate FLP by preventing formation of metal-induced gap states (MIGS) with its very low tunneling resistance and series resistance and can provide very small electron energy barrier at the metal/TiO2 interface. The GeO2 layer can induce further alleviation of FLP by reducing interface state density (D-it) on Ge which is one of main causes of FLP. Moreover, the proposed TiO2/GeO2 stack can minimize interface dipole formation which induces the SBH increase. The M-I-S structure incorporating the TiO2/GeO2 interlayer stack achieves a perfect ohmic characteristic, which has proved unattainable with a single interlayer. FLP can be perfectly alleviated, and the SBH of the metal/n-Ge can be tremendously reduced. The proposed structure (Ti/TiO2/GeO2/n-Ge) exhibits 0.193 eV of effective electron SBH which achieves 0.36 eV of SBH reduction from that of the Ti/n-Ge structure. The proposed M-I-S structure can be suggested as a promising S/D contact technique for nanoscale Ge n-channel transistors to overcome the large electron SBH problem caused by severe FLP.
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Collections - College of Engineering > Department of Mechanical Engineering > 1. Journal Articles
- College of Engineering > School of Electrical Engineering > 1. Journal Articles
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