A two-sensor 3ω-2ω method for thermal boundary resistance measurement

Thermal boundary resistance (TBR), which measures an interface's resistance to the thermal flow, is of critical importance among various areas, such as electronics cooling and thermoelectric materials. As for measuring TBR, electrical techniques are generally less sensitive compared to optical ones, but they are easily operable and compatible with the measurement of other electric properties; thus, it is highly desirable to develop electrical methods with higher accuracy and larger measurement range. Here, a two-sensor 3 omega -2 omega method with a novel experimental procedure design is proposed, which can well address those deficiencies in the conventional 3 omega method. Two parallel metal sensors are fabricated, with one of them being wide and the other being narrow. The temperature changes of these two sensors are measured by detecting the 3 omega and 2 omega signals, respectively. The measurement includes three steps: (1) obtain thin film's thermal conductivity from the wide sensor's 3 omega thermal response; (2) obtain substrate thermal conductivity from the narrow sensor's 2 omega thermal response; and (3) derive an effective TBR from the narrow sensor's 3 omega thermal response. Moreover, it is found the TBRs of metal/dielectric and dielectric/substrate interfaces are distinguishable due to the considerable difference between their contact areas, which enables us to separate these two TBRs by varying the contact area (heater's width). Then, our method is employed to probe the TBRs between the Al2O3 nanofilm and Si as well as SiC substrates at room temperature and good agreement with the previous measurements is achieved, verifying its feasibility. Our present scheme will be helpful for the experimental study of interfacial thermal transport.