Unexpected scaling of the performance of carbon nanotube Schottky-barrier transistors

Physical Review B - Condensed Matter and Materials Physics

Volumn 68, Issue 23, 2003, Pages

  Heinze, S ^a   Radosavljevic M ^a   Tersoff, J ^a   Avouris, Ph ^a  

^a IBM T J WATSON RESEARCH CENTER   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CARBON;

ANALYTIC METHOD; ARTICLE; CALCULATION; CONDUCTANCE; DEVICE; DIELECTRIC CONSTANT; ELECTRIC POTENTIAL; ENERGY; MATHEMATICAL ANALYSIS; MEASUREMENT; MODEL; NANOTUBE; PARAMETER; PERFORMANCE; PHYSICS; SCALE UP; SEMICONDUCTOR; THICKNESS;

EID: 0842343398     PISSN: 10980121     EISSN: 1550235X     Source Type: Journal    
DOI: 10.1103/PhysRevB.68.235418     Document Type: Article

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17. More accurate methods are available; see S. Datta, Electronic Transport in Mesoscopic Systems (Cambridge University Press, Cambridge, 1995). However, WKB is sufficient for our application. The transmission factor for tunneling is very low in the turn-on regime, so a careful treatment of the non-equilibrium charge is unnecessary. The current varies over orders of magnitude, so high precision is not essential, and absolute accuracy is limited by the absence of detailed structural information regarding the metal-nanotube contact.
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19. The main effect of charge on the NT (which we neglect) is to alter the potential within the NT channel. Source and drain SB’s are relatively unaffected in the energy range of significant tunneling current. The current is limited by the channel only when there is negligible charge in the channel. As a result, the approximation gives a good description of the current [except perhaps in the fully “On” regime (Ref. 22)], and so does not affect our conclusions.
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21. ox persists. Thus our experimental findings can be adequately modeled using long-channel devices at ideal saturation and vanishing drain barrier.
22. This interpretation is supported by transmission electron microscopy images of the device cross section, which show that our source/drain contacts are not nearly as sharp and perpendicular to the substrate as assumed in the simulation.
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24. In the regime of full turn-on, if the Schottky barriers become sufficiently transparent, other factors can come into play in determining the current. Then effects that we neglect can become significant, including the (non-equilibrium) charge in the NT channel. Thus the gate-channel capacitance (and hence the dielectric constant) affects the maximum On-current, see J. Guo, S. Datta, and M. Lundstrom, cond-mat/0306199, IEEE Trans. Electron Devices (to be published).