Thermal Conductance between <6 nm Single-Walled Carbon Nanotube Bundle and Si Substrate

Interfacial thermal conductance between a single-walled carbon nanotube (SWCNT) and substrate is rarely characterized and understood due to substantial challenges in probing the energy transport across such nm-wide contact. Here, we report the interfacial thermal conductance between a <6 nm thick SWCNT bundle and Si substrate. The energy transport state-resolved Raman is employed for the measurement, where the Raman spectrum change under continuous wave (CW) and 20 ns pulsed laser heating is measured for the thermal response of the SWCNT under steady and transient heat conduction sustained by the interfacial thermal conductance. Since no knowledge is needed for laser absorption and temperature rise of the sample, the measurement achieves extreme capability and confidence. For three locations of the SWCNT bundle, the interfacial thermal resistance is measured to be (2.98 ± 0.22) × 103, (3.01 ± 0.23) × 103, and (1.67 ± 0.27) × 103 K m W–1, corresponding to thermal conductance in a range (3.3–6.0) × 10–4 W m–1 K–1. Our analysis suggests a loose contact between the SWCNT bundle and the Si substrate, mainly attributed to the obvious nonuniformity of the sample, which was resolved by atomic force microscopy and Raman spectroscopy. For an assumed contact width of ∼1 nm, the interfacial thermal resistance would be of the order of 10–6 W m–2 K–1, in line with those reported for mechanically exfoliated graphene and two-dimensional (2D) materials.