title: Simultaneous measurement of thermal conductivity and heat capacity of bulk and thin film materials using frequency-dependent transient thermoreflectance method.
abstract: The increasing interest in the extraordinary thermal properties of nanostructures has led to the development of various measurement techniques. Transient thermoreflectance method has emerged as a reliable measurement technique for thermal conductivity of thin films. In this method, the determination of thermal conductivity usually relies much on the accuracy of heat capacity input. For new nanoscale materials with unknown or less-understood thermal properties, it is either questionable to assume bulk heat capacity for nanostructures or difficult to obtain the bulk form of those materials for a conventional heat capacity measurement. In this paper, we describe a technique for simultaneous measurement of thermal conductivity κ and volumetric heat capacity C of both bulk and thin film materials using frequency-dependent time-domain thermoreflectance (TDTR) signals. The heat transfer model is analyzed first to find how different combinations of κ and C determine the frequency-dependent TDTR signals. Simultaneous measurement of thermal conductivity and volumetric heat capacity is then demonstrated with bulk Si and thin film SiO2 samples using frequency-dependent TDTR measurement. This method is further testified by measuring both thermal conductivity and volumetric heat capacity of novel hybrid organic-inorganic thin films fabricated using the atomic∕molecular layer deposition. Simultaneous measurement of thermal conductivity and heat capacity can significantly shorten the development∕discovery cycle of novel materials.
authors.affiliation: Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Jie
authors.initials: J
authors.lastname: Zhu
authors.forename: Miao
authors.initials: M
authors.lastname: Tian
authors.forename: Xiaokun
authors.initials: X
authors.lastname: Gu
authors.forename: Aaron
authors.initials: A
authors.lastname: Schmidt
authors.forename: Ronggui
authors.initials: R
authors.lastname: Yang
mesh_terms: D004553:Electric Conductivity; D004867:Equipment Design; D006358:Hot Temperature; D008422:Materials Testing / Q000379:methods*; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D012825:Silicon / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013696:Temperature; D013814:Thermal Conductivity
chemical_list: D012822:Silicon Dioxide; D012825:Silicon