Variability and high temperature reliability of graphene field-effect transistors with thin epitaxial CaF2 insulators

Illarionov，Yu Yu1,2,3; Knobloch，T.2; Uzlu，B.4; Banshchikov，A. G.3; Ivanov，I. A.3; Sverdlov，V.2; Otto，M.4; Stoll，S. L.4; Vexler，M. I.3; Waltl，M.2; Wang，Z.4; Manna，B.2; Neumaier，D.4,5; Lemme，M. C.4,6; Sokolov，N. S.3; Grasser，T.2

2024-12-01

10.1038/s41699-024-00461-0

npj 2D Materials and Applications   影响因子和分区

2397-7132

Graphene is a promising material for applications as a channel in graphene field-effect transistors (GFETs) which may be used as a building block for optoelectronics, high-frequency devices and sensors. However, these devices require gate insulators which ideally should form atomically flat interfaces with graphene and at the same time contain small densities of traps to maintain high device stability. Previously used amorphous oxides, such as SiO and AlO, however, typically suffer from oxide dangling bonds at the interface, high surface roughness and numerous border oxide traps. In order to address these challenges, here we use 2 nm thick epitaxial CaF as a gate insulator in GFETs. By analyzing device-to-device variability for about 200 devices fabricated in two batches, we find that tens of them show similar gate transfer characteristics. Our statistical analysis of the hysteresis up to 175C has revealed that while an ambient-sensitive counterclockwise hysteresis can be present in some devices, the dominant mechanism is thermally activated charge trapping by border defects in CaF which results in the conventional clockwise hysteresis. We demonstrate that both the hysteresis and bias-temperature instabilities in our GFETs with CaF are comparable to similar devices with SiO and AlO. In particular, we achieve a small hysteresis below 0.01 V for equivalent oxide thickness (EOT) of about 1 nm at the electric fields up to 15 MV cm and sweep times in the kilosecond range. Thus, our results demonstrate that crystalline CaF is a promising insulator for highly-stable GFETs.

SCI

英语

第一

2-s2.0-85188138852

Scopus

1.Department of Materials Science and Engineering,Southern University of Science and Technology,Shenzhen,1088 Xueyuan Blvd,518055,China
2.Institute for Microelectronics (TU Wien),Vienna,Gusshausstrasse 27–29,1040,Austria
3.Ioffe Institute,St-Petersburg,Polytechnicheskaya 26,194021,Russian Federation
4.AMO GmbH,Aachen,Otto-Blumenthal-Strasse 25,52074,Germany
5.Bergische Universitat Wuppertal,Wuppertal,Gaussstrasse 20,42119,Germany
6.Chair of Electronic Devices,RWTH Aachen Univeristy,Aachen,Otto-Blumenthal-Str. 25,52074,Germany

Illarionov，Yu Yu,Knobloch，T.,Uzlu，B.,et al. Variability and high temperature reliability of graphene field-effect transistors with thin epitaxial CaF2 insulators[J]. npj 2D Materials and Applications,2024,8(1).

Illarionov，Yu Yu.,Knobloch，T..,Uzlu，B..,Banshchikov，A. G..,Ivanov，I. A..,...&Grasser，T..(2024).Variability and high temperature reliability of graphene field-effect transistors with thin epitaxial CaF2 insulators.npj 2D Materials and Applications,8(1).

Illarionov，Yu Yu,et al."Variability and high temperature reliability of graphene field-effect transistors with thin epitaxial CaF2 insulators".npj 2D Materials and Applications 8.1(2024).