Quantitative Thermal Imaging of Single-Walled Carbon Nanotube Devices by Scanning Joule Expansion Microscopy

Abstract

Electrical generation of heat in single-walled carbon nanotubes (SWNTs) and subsequent thermal transport into the surroundings can critically affect the design, operation, and reliability of electronic and optoelectronic devices based on these materials. Here we investigate such heat generation and transport characteristics in perfectly aligned, horizontal arrays of SWNTs integrated into transistor structures. We present quantitative assessments of local thermometry at individual SWNTs in these arrays, evaluated using scanning Joule expansion microscopy. Measurements at different applied voltages reveal electronic behaviors, including metallic and semiconducting responses, spatial variations in diameter or chirality, and localized defect sites. Analytical models, validated by measurements performed on different device structures at various conditions, enable accurate, quantitative extraction of temperature distributions at the level of individual SWNTs. Using current equipment, the spatial resolution and temperature precision are as good as ∼100 nm and ∼0.7 K, respectively.

Quantitative Kelvin probe force microscopy of current-carrying devices

“…Besides efficiency, this fact allows FM-KPFM to directly image anomalous resistances or device-specific behaviors, 30 including those which cannot be accounted for by scanned probe techniques that do not spatially resolve potential profiles. [31][32][33] Closer to the drain and source electrodes, the DV SWNT (x,V D ) curves in Fig. 3(c) become steeper.…”

The critical power to maintain thermally stable molecular junctions

“…On the other hand, the presence of interface critically defines underlying physical processes at atomic-scale, such as heat or electronic transport across the tip-sample contact in the scanning thermal microscope (SThM) 9,10 , scanning tunnelling microscope (STM) 11 , as well as thermoelectric energy conversion in molecular junctions 12 . Although limited by technical challenges, there are increasing activities focusing on the structural, electronic and thermal behaviours of atomic-scale junctions through experimental and theoretical approaches [12][13][14][15][16][17][18][19][20] , as well as mechanistic studies of SThM and STM 10,[21][22][23] . For example, Huang et al 24 probed the effective temperature of single-molecule junctions with currentinduced local heating as a function of molecular length and applied bias voltage.…”

A Survey of Carbon Nanotube Interconnects for Energy Efficient Integrated Circuits

“…Scanning Joule Expansion Microscopy (SJEM) has been applied to study the thermal properties of an array of parallel, single CNT lines embedded in PMMA [109]. By measuring the thermal expansion of the CNTs and the surrounding PMMA -metallic and semiconducting CNTs could be distinguished, the local temperature could be obtained with a lateral resolution of 100 nm and local hot-spot formation could be observed.…”

“…One such approach, in which the passive atomic force microscope (AFM) tip is replaced with a nanoscale thermocouple [110], has been applied to single CNTs [109]. Self-heating of a single CNT could be resolved with a lateral resolution of 50 nm.…”