Nanoscale Calorimetry Using a Suspended Bridge Configuration

Abstract A new setup for small-scale differential scanning calorimetry (DSC) studies based on a suspended bridge configuration is presented. The new setup has three major advantages over previously reported DSC setups: 1) superior temperature uniformity in the bridge cross section; 2) less heat loss to the surroundings by at least two orders of magnitude; and 3) a faster transient response by three orders of magnitude. This paper includes a thermal analysis to support these improvements. A major contribution of the new thermal analysis over previous reports is the inclusion of the thermal mass of the substrate in calculations, which makes thermal design more detailed, dramatically affecting accuracy and sensitivity in measurements. Furthermore, the new thermal analysis more accurately accounts for heat loss to the substrate and the surroundings in efforts to resolve suspected inconsistencies in previously reported data. Experimental validation of the new setup is presented by measuring the specific heat of thin layers of Si0₂ and CoFe. The specific heat of Si0₂ was found to be 2.2 times 10⁶ Jm ^-3 K^-1 which is nearly 10% different from the literature values of bulk specimens. For CoFe, the specific heat value of 3.16 x 10⁶ Jm ^-3 K^-1 is obtained using differential Cu/Si0₂ and Cu/Si0₂/CoFe structures compared to the value of 3.5 times 10⁶ Jm ^-3 K^-1 obtained using single CoFe suspended structure.