Article

Device study, chemical doping, and logic circuits based on transferred aligned single-walled carbon nanotubes

Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, USA
Applied Physics Letters (Impact Factor: 3.52). 08/2008; 93(3):033101 - 033101-3. DOI: 10.1063/1.2956677
Source: IEEE Xplore

ABSTRACT In this paper, high-performance back-gated carbon nanotube field-effect transistors based on transferred aligned carbon nanotubes were fabricated and studies found that the on/off ratio can reach 107 and the current density can reach 1.6 μ A /μ m after electrical breakdown. In addition, chemical doping with hydrazine was used to convert the p -type aligned nanotube devices into n -type. These devices were further utilized to demonstrate various logic circuits, including p -type metal-oxide-semiconductor inverters, diode-loaded inverters, complementary metal-oxide-semiconductor inverters, NAND, and NOR gates. This approach could work as the platform for future nanotube-based nanoelectronics.

Download full-text

Full-text

Available from: H.-S. Philip Wong, Jul 28, 2015
0 Followers
 · 
107 Views
  • Source
    • "Nevertheless, the high temperature needed for good quality CNT growth is incompatible with current CMOS technologies [10]. Alternatively , various methods for CNT assembly in the post-synthetic regime have been developed [11] [12] [13] [14] [15] [16]. Among then, acdielectrophoresis (DEP) using an ac electric field to integrate CNTs onto pre-patterned electrodes has proven its potential [17]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We report a novel resist-assisted dielectrophoresis method for single-walled carbon nanotube (SWCNT) assembly. It provides nanoscale control of the location, density, orientation and shape of individual SWCNTs. Sub-50 nm accuracy and a yield higher than 85% have been achieved. Using the method, we demonstrate suspended-body SWCNT field-effect transistors (FETs) with back-gate and sub-100 nm air-gap lateral-gate configurations. The suspended-body SWCNT FETs show excellent electrical characteristics with Ion/Ioff ∼ 107, ultra-low off currents ∼10−14 A and small subthreshold swings. The technique contributes to the ultimate solution for bottom-up fabrication of a broad field of CNT-based devices, such as: complementary metal–oxide-semiconductor and nano-electrical–mechanical-system devices for sensing and radio-frequency applications. Moreover, the versatile method could be applied to the assembly of many other promising materials, such as: nanowires and graphene flakes.
    Carbon 04/2012; 50(5):1720–1726. DOI:10.1016/j.carbon.2011.12.006 · 6.16 Impact Factor
  • Source
    • "Hence, chemical doping of nanotubes provides an efficient way to control the electrical properties of CNTFETs. It has been reported that p-type CNTFETs can be converted to n-type via potassium doping [4], by functional groups existing in polymers and molecules [5] [3] [6]. Modulation of nanotube device performance while maintaining its p-type behavior, however, is very important for electronic applications. "
    [Show abstract] [Hide abstract]
    ABSTRACT: A simple, reliable, and large scale ambient environment doping method for carbon nanotubes is a highly desirable approach for modulating the performance of nanotube based electronics. One of the major challenges is doping carbon nanotubes to simultaneously offer a large shift in threshold voltage and an improved subthreshold swing. In this paper, we report on modulating the performance of carbon nanotube field-effect transistors (CNTFETs) by rationally selecting doping molecules. We demonstrated that Rose Bengal sodium salt (RB-Na) molecular doping can effectively shift the threshold voltage (ΔVth) of CNTFETs up to ∼6 V, decrease the subthreshold swing down to 130 mV/decade, and increase the effective field-effect mobility to 5 cm2 V(-1) s(-1). It is also shown that CNTFETs doped with Rose Bengal lactone (RBL) show a smaller variation in ΔVth (∼2 V) and subthreshold swing than those doped by RB-Na, which can be attributed to the difference in their molecular structures. The observed right-shift of the threshold voltage is attributed to the positive charge doping of the nanotube conduction channel from Rose Bengal molecules. The resultant lowering of the subthreshold swing is due to the reduced Schottky barrier at the CNT/metal/molecule interface. This room temperature chemical doping approach provides an efficient, simple, and cost-effective method to fabricate highly reliable and high-performance nanotube transistors for future nanotube based electronics.
    Nanotechnology 11/2011; 22(45):455202. DOI:10.1088/0957-4484/22/45/455202 · 3.67 Impact Factor
  • Source
    • "From Fig. 4(d), after the electrical breakdown, I on /W is 8.3 μA/μm and g m /W is 2.2 μS/μm. Compared with the results from devices fabricated using aligned nanotubes with typical density (5 tubes/μm) reported in our previous publication (I on /W = 1.7 μA/μm and g m /W = 0.28 μS/μm) [24], the values of I on /W and g m /W reported here are 5 times and 8 times better, respectively. The improvements are due to both the higher nanotube density and the adoption of a high-κ gate dielectric. "
    [Show abstract] [Hide abstract]
    ABSTRACT: For nanotube-based electronics to become a viable alternative to silicon technology, high-density aligned carbon nanotubes are essential. In this paper, we report the combined use of low-pressure chemical vapor deposition and stacked multiple transfer to achieve high-density aligned nanotubes. By using an optimized nanotube synthesis recipe, we have achieved high-density aligned carbon nanotubes with density as high as 30 tubes/μm. In addition, a facile stacked multiple transfer technique has been developed to further increase the nanotube density to 55 tubes/μm. Furthermore, high-performance submicron carbon nanotube field-effect transistors have been fabricated on the high-density aligned nanotubes. Before removing the metallic nanotubes by electrical breakdown, the devices exhibit on-current density of 92.4 μA/μm and normalized transconductance of 13.3 μS/μm. Moreover, benchmarking with the aligned carbon nanotube transistors in the literature indicates that our devices exhibit the best performance so far, which is attributed to both the increased nanotube density and scaling down of channel length. This study shows the great potential of using such high-density aligned nanotubes for high performance nanoelectronics and analog/RF applications. KeywordsAligned carbon nanotubes-chemical vapor deposition-high-density-high performance transistors
    Nano Research 12/2010; 3(12):831-842. DOI:10.1007/s12274-010-0054-0 · 6.96 Impact Factor
Show more