200 research outputs found
Interacting Systems for Self-Correcting Low Power Switching
In this paper we first show that dynamic switching schemes can be used to
reduce energy dissipation below the thermodynamic minimum of NkTlnr (N= number
of state variables, 1/r=error probability), but only at the expense of the
error immunity inherent in thermodynamic processes for which the final state is
insensitive to the switching dynamics. It is further shown that, for a system
which has internal feedback, e.g. nanomagnets, such that all N spins act in
concert, it should be possible to switch with an energy dissipation of the
order of kTlnr (considerably less than the thermodynamic limit of NkTlnr),
while retaining an error immunity comparable to thermodynamic switching
High Performance Molybdenum Disulfide Amorphous Silicon Heterojunction Photodetector
One important use of layered semiconductors such as molybdenum disulfide
(MoS2) could be in making novel heterojunction devices leading to
functionalities unachievable using conventional semiconductors. Here we
demonstrate an ultrafast metal-semiconductor-metal heterojunction
photodetector, made of MoS2 and amorphous silicon (a-Si), with rise and fall
times of about 0.3 ms. This is more than an order of magnitude improvement over
response times of conventional a-Si (~5 ms) and best reported MoS2 devices (~50
ms). The van-der-waals heterojunction presented here yields a high
photoresponsivity of 210 mA/W at green light-the wavelength used in commercial
imaging systems. This responsivity is 4X larger than that of the best MoS2
devices, and 2X larger than that of commercial a-Si devices. The 10X
improvement in speed with high photoresponsivity provides a potential solution
to a decades-long problem for thin film imagers and could find applications in
large area electronics such as biomedical imaging and x-ray fluoroscopy
Role of Phonon Scattering in Graphene Nanoribbon Transistors: Non-Equilibrium Green's Function Method with Real Space Approach
Mode space approach has been used so far in NEGF to treat phonon scattering
for computational efficiency. Here we perform a more rigorous quantum transport
simulation in real space to consider interband scatterings as well. We show a
seamless transition from ballistic to dissipative transport in graphene
nanoribbon transistors by varying channel length. We find acoustic phonon (AP)
scattering to be the dominant scattering mechanism within the relevant range of
voltage bias. Optical phonon scattering is significant only when a large gate
voltage is applied. In a longer channel device, the contribution of AP
scattering to the dc current becomes more significant
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