Toward surround gates on vertical single-walled carbon nanotube devices

Abstract

The one-dimensional, cylindrical nature of single-walled carbon nanotubes ͑SWCNTs͒ suggests that the ideal gating geometry for nanotube field-effect transistors ͑FETs͒ is a surround gate ͑SG͒. Using vertical SWCNTs templated in porous anodic alumina, SGs are formed using top-down processes for the dielectric/metal depositions and definition of the channel length. Surround gates allow aggressive scaling of the channel to 25% of the length attainable with a bottom-gate geometry without incurring short-channel effects. The process demonstrated here for forming SGs on vertical SWCNTs is amenable for large-scale fabrication of multinanotube FETs.

Microfabrication of Vertical Carbon Nanotube Field-Effect Transistors on an Anodized Aluminum Oxide Template Using Atomic Layer Deposition

“…However, since vertical growth of CNTs and integration of the gates with the vertical CNTs are challenging, only limited works on fabrication of vertical CNT-based devices have been reported. Recently, gated/vertical CNTs were fabricated on an anodized aluminum oxide (AAO) template where CNTs were vertically oriented inside the pores, but no successful I-V characterizations of the fabricated CNT devices for verification was demonstrated [4]. To the best knowledge of the author, no successful demonstration of fabrication of the vertical CNT-based FETs has been reported.…”

“…2 (c)). The electrodeposition was carried at a current density of 50 mA/cm 2 for 10 ms in a solution containing Pd(NH3) 4 Cl 2 -NH 4 Cl. After electrodeposition, Pd cluster appeared in cubic forms at the top surface of the AAO template, confirming that the electrodeposited Pd contacted the CNTs at the bottom of the pores, making the vertical conductive ways.…”

Enhanced Control of Single-Walled Carbon Nanotube Properties Using MPCVD with DC Electrical Bias

“…Though this technique successfully aligns individual SWNTs within the confined vertical pores, the free ends of SWNTs emerging from the pores adhere strongly to the top horizontal PAA surface rather than maintaining vertical alignment. SWNT functionalization within the vertical pore structure has been achieved (Franklin, et al, 2009a;Franklin, et al, 2009b), though the misaligned SWNTs on the top surface of the template may be unattractive for some applications. Assembly of freestanding vertical SWNTs from solution post-synthesis is also achievable through electrophoresis into predefined vertical vias etched in a silicon nitride mask (Goyal, et al, 2008).…”

Electrical Excitation of Surface Plasmons by an Individual Carbon Nanotube Transistor

“…The EL emission intensity is depending on the impact excitation rate with an exponent equal to [−F th /F app ], where F app is the effective electric field applied to the metal-nanotube interface [25]. This electric field can be expressed as F app = [γV DS + (V GS − V T )]/λ scr , where γ is the fraction of V DS contributing to the impact excitation rate, λ scr is the screening length that represents the length over which the potential drops within the metal-nanotube junction [28] and V T is the turn-on voltage for the device. Thus, EL emission intensity (S el ) is given by the expression:…”

“…The screening length for impact excitation in SWNTFET devices can be expressed as [28] λ scr = ǫ cnt d cnt t ox /ǫ ox , where ǫ cnt and d cnt are the dielectric constant and diameter of the CNT, respectively and ǫ ox and t ox are the dielectric constant and thickness of the oxide layer, respectively. The screening length is estimated to be ∼30 nm by using of ǫ cnt =18 [29], ∼25 cm 2 V/s for holes are deduced by a straight line fitting of the transfer characteristics with transport equation (Fig.…”