Thermal boundary resistance and thermal rectification in VACNT arrays integrated with SnZn alloys

Abstract

Thermal rectification (TR) phenomena in carbon nanotubes (CNTs) have been previously foreseen through theoretical predictions; however, its experimental realization in bulk CNT arrays remains relatively unexplored. Herein, we have synthesized vertically aligned carbon nanotube (VACNT) arrays of ∼ 4.5 mm in length on a 4-inch silicon wafer by a combined bubble-assisted chemical vapor deposition method. By integrating these VACNT arrays with SnZn alloys, we have successfully developed devices capable of functioning across a wide temperature range spanning from 200 °C to 400 °C. Notably, the thermal boundary resistances (TBR) between the VACNTs and SnZn alloy exhibit pronounced dependence on the alloy's composition, exhibiting variations ranging from 0.12 cm2KW−1 to 1.12 cm2KW−1. Of particular significance, the TBRs of Sn50Zn50/VACNT compounds in the forward direction were found to fall within the range of 0.63–0.98 cm2KW−1 in the temperature range from120 °C to 180 °C, while in the backward direction, they exhibited values in the range of 0.13–0.34 cm2KW−1. These contrasting TBR values highlight a marked thermal rectification performance with a substantial TR coefficient between 0.49 and 0.66. Our comprehensive investigation sheds valuable insights into the TR effects within VACNTs and metal/alloy interfaces, presenting a promising avenue for the development of future thermal logic circuits and thermal transistors.