Abstract

Hydrogen-terminated molecular nano-diamonds, also known as diamondoids, attract much attention in the field of nanoelectronics due to their outstanding properties. Diamondoids exhibit high thermodynamic stability, good mechanical strength, negative electron affinity, and short electron mean free paths. Their potential applications for nanotechnology include robust mechanical coatings, highly efficient electron cathodes, and seed crystals for diamond growth. Past studies have provided considerable information on several properties of self-assembled monolayers (SAMs) of diamondoids, including their orientational and electronic structure, dielectric properties, and electron-emission properties. However, little work has been done on characterizing thermal transport through SAMs of diamondoids.

In this work, we use picosecond time domain thermoreflectance (TDTR) to investigate the thermal properties of two thiol-functionalized diamondoids: Adamantane-1-thiol and [121]tetramantane-6-thiol, which are sandwiched between gold (Au) and aluminum (Al). In particular, we measure the thermal conductance of Al-diamondoid SAM-Au junctions. Preliminary measurements indicate that the thermal conductance is 41.3 ± 4.7 MWm-2K-1 for the SAMs of adamantane-1-thiol and 36.3 ± 2.8 MWm-2K-1 for the SAMs of [121]tetramantane-6-thiol. We also study SAMs of diamondoid-thiols on platinum (Pt) for comparison with the SAMs of diamondoid-thiols on Au. Thermal conductance data for other types of SAMs such as mercaptoethanol and dodecanethiol are also presented for comparison. We will discuss the impact of the strength of substrate-molecule bonding on phonon heat transport across the interface.