6 research outputs found
Insulators for 2D nanoelectronics: the gap to bridge
Nanoelectronic devices based on 2D materials are far from delivering their full theoretical performance potential due to the lack of scalable insulators. Amorphous oxides that work well in silicon technology have ill-defined interfaces with 2D materials and numerous defects, while 2D hexagonal boron nitride does not meet required dielectric specifications. The list of suitable alternative insulators is currently very limited. Thus, a radically different mindset with respect to suitable insulators for 2D technologies may be required. We review possible solution scenarios like the creation of clean interfaces, production of native oxides from 2D semiconductors and more intensive studies on crystalline insulators
Insulators for 2D nanoelectronics: the gap to bridge
Nanoelectronic devices based on 2D materials are far from delivering their full theoretical performance potential due to the lack of scalable insulators. Amorphous oxides that work well in silicon technology have ill-defined interfaces with 2D materials and numerous defects, while 2D hexagonal boron nitride does not meet required dielectric specifications. The list of suitable alternative insulators is currently very limited. Thus, a radically different mindset with respect to suitable insulators for 2D technologies may be required. We review possible solution scenarios like the creation of clean interfaces, production of native oxides from 2D semiconductors and more intensive studies on crystalline insulators
Variability and Reliability of Graphene Field-Effect Transistors with CaF2 Insulators
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 SiO2 and
Al2O3, 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 for the first time 2nm thick epitaxial CaF2 as a
gate insulator in GFETs. By analyzing device-to-device variability for over 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 CaF2 which results in the conventional clockwise
hysteresis. We demonstrate that both the hysteresis and bias-temperature
instabilities in our GFETs with CaF2 are comparable to similar devices with
SiO2 and Al2O3. 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 CaF2 is a promising insulator for highly-stable GFETs