PMID- 33410418
OWN - NLM
STAT- Publisher
LR  - 20240222
IS  - 1361-6528 (Electronic)
IS  - 0957-4484 (Linking)
VI  - 32
IP  - 13
DP  - 2021 Jan 7
TI  - Understanding ambipolar transport in MoS(2) field effect transistors: the 
      substrate is the key.
PG  - 135202
LID - 10.1088/1361-6528/abd27a [doi]
AB  - 2D materials offer a pathway for further scaling of CMOS technology. However, for 
      this to become a reality, both n-MOS and p-MOS should be realized, ideally with 
      the same (standard) material. In the specific case of MoS(2) field effect 
      transistors (FETs), ambipolar transport is seldom reported, primarily due to the 
      phenomenon of Fermi level pinning (FLP). In this study we identify the possible 
      sources of FLP in MoS(2) FETs and resolve them individually. A novel contact 
      transfer technique is used to transfer contacts on top of MoS(2) flake devices 
      that results in a significant increase in the hole branch of the transfer 
      characteristics as compared to conventionally fabricated contacts. We hypothesize 
      that the pinning not only comes from the contact-MoS(2) interface, but also from 
      the MoS(2)-substrate interface. We confirm this by shifting to an hBN substrate 
      which leads to a 10 fold increase in the hole current compared to the SiO(2) 
      substrate. Furthermore, we analyse MoS(2) FETs of different channel thickness on 
      three different substrates, SiO(2), hBN and Al(2)O(3), by correlating the 
      p-branch I (ON)/I (OFF) to the position of oxide defect band in these substrates. 
      FLP from the oxide is reduced in the case of Al(2)O(3) which enables us to 
      observe ambipolar transport in a bilayer MoS(2) FET. These results highlight that 
      MoS(2) is indeed an ambipolar material, and the absence of ambipolar transport in 
      MoS(2) FETs is strongly correlated to its dielectric environment and processing 
      conditions.
FAU - Mootheri, Vivek
AU  - Mootheri V
AD  - Department of Materials Engineering (MTM), KU Leuven, Belgium. IMEC, Kapeldreef 
      75, Leuven, Belgium.
FAU - Leonhardt, Alessandra
AU  - Leonhardt A
FAU - Verreck, Devin
AU  - Verreck D
FAU - Asselberghs, Inge
AU  - Asselberghs I
FAU - Huyghebaert, Cedric
AU  - Huyghebaert C
FAU - de Gendt, Stefan
AU  - de Gendt S
FAU - Radu, Iuliana
AU  - Radu I
FAU - Lin, Dennis
AU  - Lin D
FAU - Heyns, Marc
AU  - Heyns M
LA  - eng
PT  - Journal Article
DEP - 20210107
PL  - England
TA  - Nanotechnology
JT  - Nanotechnology
JID - 101241272
SB  - IM
EDAT- 2021/01/08 06:00
MHDA- 2021/01/08 06:00
CRDT- 2021/01/07 08:39
PHST- 2021/01/07 08:39 [entrez]
PHST- 2021/01/08 06:00 [pubmed]
PHST- 2021/01/08 06:00 [medline]
AID - 10.1088/1361-6528/abd27a [doi]
PST - aheadofprint
SO  - Nanotechnology. 2021 Jan 7;32(13):135202. doi: 10.1088/1361-6528/abd27a.