Abstract
The difficulty in Schottky barrier height (SBH) control arising from Fermi-level pinning (FLP) at electrical contacts is a bottleneck in designing high-performance nanoscale electronics and optoelectronics based on molybdenum disulfide (MoS2). For electrical contacts of multilayered MoS2, the Fermi level on the metal side is strongly pinned near the conduction-band edge of MoS2, which makes most MoS2-channel field-effect transistors (MoS2 FETs) exhibit n-type transfer characteristics regardless of their source/drain (S/D) contact metals. In this work, SBH engineering is conducted to control the SBH of electrical top contacts of multilayered MoS2 by introducing a metal-interlayer-semiconductor (MIS) structure which induces the Fermi-level unpinning by a reduction of metal-induced gap states (MIGS). An ultrathin titanium dioxide (TiO2) interlayer is inserted between the metal contact and the multilayered MoS2 to alleviate FLP and tune the SBH at the S/D contacts of multilayered MoS2 FETs. A significant alleviation of FLP is demonstrated as MIS structures with 1 nm thick TiO2 interlayers are introduced into the S/D contacts. Consequently, the pinning factor (S) increases from 0.02 for metal-semiconductor (MS) contacts to 0.24 for MIS contacts, and the controllable SBH range is widened from 37 meV (50-87 meV) to 344 meV (107-451 meV). Furthermore, the Fermi-level unpinning effect is reinforced as the interlayer becomes thicker. This work widens the scope for modifying electrical characteristics of contacts by providing a platform to control the SBH through a simple process as well as understanding of the FLP at the electrical top contacts of multilayered MoS2.
| Original language | English |
|---|---|
| Pages (from-to) | 6292-6300 |
| Number of pages | 9 |
| Journal | ACS Nano |
| Volume | 12 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - 2018 Jun 26 |
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Keywords
- Fermi-level unpinning
- metal-induced gap states
- metal-interlayer-semiconductor structure
- molybdenum disulfide
- Schottky barrier height
ASJC Scopus subject areas
- Materials Science(all)
- Engineering(all)
- Physics and Astronomy(all)
Cite this
Schottky Barrier Height Engineering for Electrical Contacts of Multilayered MoS2 Transistors with Reduction of Metal-Induced Gap States. / Kim, Gwang Sik; Kim, Seung Hwan; Park, June; Han, Kyu Hyun; Kim, Jiyoung; Yu, Hyun-Yong.
In: ACS Nano, Vol. 12, No. 6, 26.06.2018, p. 6292-6300.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Schottky Barrier Height Engineering for Electrical Contacts of Multilayered MoS2 Transistors with Reduction of Metal-Induced Gap States
AU - Kim, Gwang Sik
AU - Kim, Seung Hwan
AU - Park, June
AU - Han, Kyu Hyun
AU - Kim, Jiyoung
AU - Yu, Hyun-Yong
PY - 2018/6/26
Y1 - 2018/6/26
N2 - The difficulty in Schottky barrier height (SBH) control arising from Fermi-level pinning (FLP) at electrical contacts is a bottleneck in designing high-performance nanoscale electronics and optoelectronics based on molybdenum disulfide (MoS2). For electrical contacts of multilayered MoS2, the Fermi level on the metal side is strongly pinned near the conduction-band edge of MoS2, which makes most MoS2-channel field-effect transistors (MoS2 FETs) exhibit n-type transfer characteristics regardless of their source/drain (S/D) contact metals. In this work, SBH engineering is conducted to control the SBH of electrical top contacts of multilayered MoS2 by introducing a metal-interlayer-semiconductor (MIS) structure which induces the Fermi-level unpinning by a reduction of metal-induced gap states (MIGS). An ultrathin titanium dioxide (TiO2) interlayer is inserted between the metal contact and the multilayered MoS2 to alleviate FLP and tune the SBH at the S/D contacts of multilayered MoS2 FETs. A significant alleviation of FLP is demonstrated as MIS structures with 1 nm thick TiO2 interlayers are introduced into the S/D contacts. Consequently, the pinning factor (S) increases from 0.02 for metal-semiconductor (MS) contacts to 0.24 for MIS contacts, and the controllable SBH range is widened from 37 meV (50-87 meV) to 344 meV (107-451 meV). Furthermore, the Fermi-level unpinning effect is reinforced as the interlayer becomes thicker. This work widens the scope for modifying electrical characteristics of contacts by providing a platform to control the SBH through a simple process as well as understanding of the FLP at the electrical top contacts of multilayered MoS2.
AB - The difficulty in Schottky barrier height (SBH) control arising from Fermi-level pinning (FLP) at electrical contacts is a bottleneck in designing high-performance nanoscale electronics and optoelectronics based on molybdenum disulfide (MoS2). For electrical contacts of multilayered MoS2, the Fermi level on the metal side is strongly pinned near the conduction-band edge of MoS2, which makes most MoS2-channel field-effect transistors (MoS2 FETs) exhibit n-type transfer characteristics regardless of their source/drain (S/D) contact metals. In this work, SBH engineering is conducted to control the SBH of electrical top contacts of multilayered MoS2 by introducing a metal-interlayer-semiconductor (MIS) structure which induces the Fermi-level unpinning by a reduction of metal-induced gap states (MIGS). An ultrathin titanium dioxide (TiO2) interlayer is inserted between the metal contact and the multilayered MoS2 to alleviate FLP and tune the SBH at the S/D contacts of multilayered MoS2 FETs. A significant alleviation of FLP is demonstrated as MIS structures with 1 nm thick TiO2 interlayers are introduced into the S/D contacts. Consequently, the pinning factor (S) increases from 0.02 for metal-semiconductor (MS) contacts to 0.24 for MIS contacts, and the controllable SBH range is widened from 37 meV (50-87 meV) to 344 meV (107-451 meV). Furthermore, the Fermi-level unpinning effect is reinforced as the interlayer becomes thicker. This work widens the scope for modifying electrical characteristics of contacts by providing a platform to control the SBH through a simple process as well as understanding of the FLP at the electrical top contacts of multilayered MoS2.
KW - Fermi-level unpinning
KW - metal-induced gap states
KW - metal-interlayer-semiconductor structure
KW - molybdenum disulfide
KW - Schottky barrier height
UR - http://www.scopus.com/inward/record.url?scp=85048030591&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85048030591&partnerID=8YFLogxK
U2 - 10.1021/acsnano.8b03331
DO - 10.1021/acsnano.8b03331
M3 - Article
C2 - 29851473
AN - SCOPUS:85048030591
VL - 12
SP - 6292
EP - 6300
JO - ACS Nano
JF - ACS Nano
SN - 1936-0851
IS - 6
ER -