Performance limits of superlattice-based steep-slope nanowire FETs

Gnani, Elena; Maiorano, P.; Reggiani, Susanna; Gnudi, A.; Baccarani, G.

doi:10.1109/iedm.2011.6131491

Cited by 18 publications

(18 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Other work has been done on steep slope devices based on GNR and CNT heterojunctions 16,17 . Gnani et al showed how superlattices could be used in a III-V nanowire FET to achieve steep slope behavior by using the superlattice gap to filter high energy electrons in the OFF state 18 . Here, we show that the recently synthesized chevron nanoribbons 19 provides a natural, monolithic material system where narrow-width energy bands and negative differential resistance (NDR) can be achieved.…”

mentioning

confidence: 99%

Negative Differential Resistance and Steep Switching in Chevron Graphene Nanoribbon Field-Effect Transistors

Smith

Llinas

Bokor

et al. 2018

IEEE Electron Device Lett.

View full text Add to dashboard Cite

Ballistic quantum transport calculations based on the non-equilbrium Green's function formalism show that field-effect transistor devices made from chevron-type graphene nanoribbons (CGNRs) could exhibit negative differential resistance with peak-to-valley ratios in excess of 4800 at room temperature as well as steepslope switching with 6 mV/decade subtheshold swing over five orders of magnitude and ON-currents of 88 µA µm −1 . This is enabled by the superlattice-like structure of these ribbons that have large periodic unit cells with regions of different effective bandgap, resulting in minibands and gaps in the density of states above the conduction band edge. The CGNR ribbon used in our proposed device has been previously fabricated with bottom-up chemical synthesis techniques and could be incorporated into an experimentally-realizable structure.In 1970, L.Esaki and R. Tsu predicted 1 that in an appropriately made superlattice, it should be possible to obtain very narrow width bands, which could then lead to negative differential resistance. The remarkable property of these superlattices is in the fact that, unlike the Esaki diodes, this negative differential resistance does not need any tunneling, rather it comes from the direct conduction of electrons. Nonetheless, significant difficulty in synthesizing atomically precise, eptiaxial heterostructures has made it very challenging to realize such superlattice structures 2-8 . Much work has been done on modeling graphene nanoribbon heterostructures and superlattices which could exhibit NDR 9-15 . Other work has been done on steep slope devices based on GNR and CNT heterojunctions 16,17 . Gnani et al. showed how superlattices could be used in a III-V nanowire FET to achieve steep slope behavior by using the superlattice gap to filter high energy electrons in the OFF state 18 . Here, we show that the recently synthesized chevron nanoribbons 19 provides a natural, monolithic material system where narrow-width energy bands and negative differential resistance (NDR) can be achieved. Our atomistic calculations predict that the NDR behavior should manifest at room temperature along with sub-thermal steepness (<60 mV/decade at room temperature). Such NDR behavior could lead to completely novel devices for next generation electronics.Unlike a graphene sheet, a narrow strip etched out of graphene, often called a graphene nanoribbon (GNR), can provide a sizeable bandgap. As a result, GNRs could lead to devices with good ON/OFF ratio at the nanoscale. However, a number of studies have also shown the deleterious effect of edge roughness on the device performance 20,21 . Recent breakthroughs in bottom-up chemical synthesis can produce GNRs with atomistically pristine edge states and overcome this shortcoming 19 . In fact, a recent experimental work demonstrated working transistors with 9-and 13-AGNRs made with these techniques 22 . The methods used to synthesize these ribbons can also be used to generate complex periodic structures beyond simply armchair and zigzag nanoribbon...

show abstract

mentioning

confidence: 99%

Negative Differential Resistance and Steep Switching in Chevron Graphene Nanoribbon Field-Effect Transistors

Smith

Llinas

Bokor

et al. 2018

IEEE Electron Device Lett.

View full text Add to dashboard Cite

show abstract

“…However, the ON-OFF ratio falls short of requirements for various ITRS technologies (http://www.itrs.net/Links/2012ITRS/Home2012.htm). The main reason for the poor off-state current is the leakage current through the Schottky barrier (Franklin et al, 2012a,b) and III-V devices (Gu et al, 2012;Dey et al, 2013) (Zhou et al, 2012;Dey et al, 2013;Moselund et al, 2012;Hu, 2008;Wang et al, 2010;Ganapathi and Salahuddin, 2011;Gnani et al, 2011;Tomioka et al, 2012). The ITRS targeted values for low operating power (LOP) and high performance (HP) technologies are highlighted (http://www.itrs.net/Links/2012ITRS/Home2012.htm).…”

Section: Itrs Requirements-2024mentioning

confidence: 97%

Carbon-based nanomaterials

Pillai

Souza

2015

Modeling, Characterization, and Production of Nanomaterials

View full text Add to dashboard Cite

“…A Newton solver is developed to solve the non-linear equation (4). Once the quasi-Fermi levels are determined, the electron density distribution in the reservoirs is obtained by (2) and the density distribution in the channel is obtained by…”

Section: Device Structure and Modeling Methodsmentioning

confidence: 99%

“…In tunnel FETs, the source valence band filters the injected electron energy distribution, reducing the S.S.; unfortunately, ION is reduced by the low PN junction tunneling probability 3 . In superlattice MOSFETs 4 , the source superlattice minigap similarly filters the injected electron energy distribution, again reducing the S.S. ; because the transmission within the superlattice miniband can approach 100%, ION can in principle be large, approaching that of conventional MOSFETs.…”

Section: Introductionmentioning

confidence: 99%

“…Reported simulations of superlattice MOSFETs predicted appealing device performances with SS values ranging from 10 to 39mV/dec 4,5,6 using coherent quantum transport models. In these models electrons travel through a quantum mechanical defined miniband coherently, even though the superlattice-shaped source contains a very high carrier density of the order of 10 18 -10 19 /cm 3 .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Performance degradation of superlattice MOSFETs due to scattering in the contacts

Long

Huang

Jiang

et al. 2016

Journal of Applied Physics

View full text Add to dashboard Cite

Ideal, completely coherent quantum transport calculations had predicted that superlattice MOSFETs may offer steep subthreshold swing performance below 60mV/dec to around 39mV/dec. However, the high carrier density in the superlattice source suggest that scattering may significantly degrade the ideal device performance. Such effects of electron scattering and decoherence in the contacts of superlattice MOSFETs are examined through a multiscale quantum transport model developed in NEMO5. This model couples NEGF-based quantum ballistic transport in the channel to a quantum mechanical density of states dominated reservoir, which is thermalized through strong scattering with local quasi-Fermi levels determined by drift-diffusion transport. The simulations show that scattering increases the electron transmission in the nominally forbidden minigap therefore degrading the subthreshold swing (S.S.) and the ON/OFF DC current ratio. This degradation varies with both the scattering rate and the length of the scattering dominated regions. Different superlattice MOSFET designs are explored to mitigate the effects of such deleterious scattering. Specifically, shortening the spacer region between the superlattice and the channel from 3.5 nm to 0 nm improves the simulated S.S. from 51mV/dec. to 40mV/dec.

show abstract

Performance limits of superlattice-based steep-slope nanowire FETs

Cited by 18 publications

References 1 publication

Negative Differential Resistance and Steep Switching in Chevron Graphene Nanoribbon Field-Effect Transistors

Negative Differential Resistance and Steep Switching in Chevron Graphene Nanoribbon Field-Effect Transistors

Carbon-based nanomaterials

Performance degradation of superlattice MOSFETs due to scattering in the contacts

Contact Info

Product

Resources

About