Chirality‐Enriched Carbon Nanotubes for Next‐Generation Computing

Abstract

electronic, [3-4,4] and functional requirements. [5] Conventional silicon integrated circuit (IC) technology faces significant challenges in meeting these demands due to its limited mechanical flexibility, high temperature processing, and scaling limitations. Emerging alternative computing platforms based on other crystalline semiconductors suffer from similar limitations. Consequently, nextgeneration computing necessitates the exploration of radically different electronic materials. Single-walled carbon nanotubes (SWCNTs) are among the most promising and highly studied nanoelectronic materials. Due to their small size, [6,7] solutionprocessability, [8] chemical stability, [9] and chirality-dependent optoelectronic properties, [10] SWCNTs offer a number of unique advantages and are compatible with the complex requirements of future computing devices. Recent advances in chiral enrichment of polydisperse SWCNTs [8,10] have allowed their use as semiconducting channels in diverse settings including charge transport devices, [2] optical emitters and detectors, [11,12] and chemical sensors. [2,3,13,14] With this tunable functionality, a range of SWCNT-based computing applications have been realized, such as printed digital logic, [15] sub-10 nm complementary metal-oxide-semiconductor (CMOS) field-effect transistors (FETs), [16] neuromorphic devices, [17] single-photon emitters (SPE), [18] and enantiomer-recognition sensors. [14] Herein, we discuss recent advances in SWCNT-based computing technologies that process, manage, and communicate information, with an emphasis on the enabling role of chiral enrichment. Section 2.1 defines the different levels of chiral enrichment. Sections 2.2 and 2.3 describe direct growth methods and post-processing purification of SWCNTs for electronic-type and monochiral enrichment. Section 3 discusses applications of electronic-type-enriched SWCNTs such as wearables, highly scaled FETs, 3D logic-memory integration, and neuromorphic devices. Section 4 outlines applications of monochiral-enriched SWCNTs including monochiral FETs, optical emitters, photodetectors, and optoelectronic ICs. Section 5 considers recent progress toward enantiomerically pure SWCNTs. Finally, Section 6 presents an outlook for SWCNTs in next-generation computing applications including a delineation of remaining challenges and future opportunities. For the past half century, silicon has served as the primary material platform for integrated circuit technology. However, the recent proliferation of nontraditional electronics, such as wearables, embedded systems, and lowpower portable devices, has led to increasingly complex mechanical and electrical performance requirements. Among emerging electronic materials, single-walled carbon nanotubes (SWCNTs) are promising candidates for next-generation computing as a result of their superlative electrical, optical, and mechanical properties. Moreover, their chirality-dependent properties enable a wide range of emerging electronic applications including sub-10 nm complementary fie...

En route to single-step, two-phase purification of carbon nanotubes facilitated by high-throughput spectroscopy

“…Unfortunately, synthesis of this carbon allotrope gives mixtures of various CNT types of drastically different properties from one another 13 . Due to the presence of multiple species in the unsorted material, the overall performance of their ensembles are far from expectations 14 , 15 . Nevertheless, purified CNT dispersions are considered very promising for applications in various fields.…”

Critical challenges and advances in the carbon nanotube–metal interface for next-generation electronics

“…Consequently, the metal-CNT interface has a critical role in the performance of the CNTFET. 165 Compared to commercial MOSFETs, CNTFETs offer minimal current leakage in the off state, can work with lower voltages (better energy-efficiency), and have 2.5−10 higher saturation velocity for carriers (Figure 7d). 166 There are several major hurdles for commercial application of CNTFETs, particularly its high contact resistance (RC) and poor interfacial interactions at the metal-CNT junction.…”

“…Studies have shown that parameters such as metal type, contact length, CNT diameter, and metal deposition method can influence the RC in CNTFETs. [164][165][166][167][168][169][170][171] The correlation between some of these parameters and RC is straightforward. For example, the contact length is inversely proportional to RC or by increasing the S-CNT diameter, the RC decreases and the optimal value can be achieved by using S-CNTs with diameters above 1.4 nm.…”

Nanoscale Patterning of Carbon Nanotubes: Techniques, Applications, and Future

“…SWCNT sorting methods have made tremendous advances recently with some sorting methods able to acquire purified SWCNT dispersions with 99.99% semiconducting chirality SWCNTs. [14,78] Selective adhesion and wrapping of rationally chosen molecules (polymers, [79] surfactants, [80] DNA [81] ) on target chirality SWCNTs is an effective and scalable technique for chirality sorting in dispersions. The sorting molecules that adhere to SWCNTs also double as the dispersing agent to create stable SWCNT dispersions.…”