AC calorimetry on thin films (d<100nm)


 

A thermal wave of high modulation frequency is generated at the surface of the thin film. Due to the high frequency of the temperature modulation, the penetration depth into the film is limited to the film thickness. This isolates the thin film thermically from the substrate and allows one to measure changes in the heat capacity and the perpendicular thermal conductance of the thin film. An ultra-thin platinum film on the surface of the film serves at the same time as heater and thermometer.  In some cases the resistance of the thin film itself may be used instead.

 
 
Magnetic transition in the heat capacity of a 300 nm thin film of La1-xCaxMnO3 on a bulk substrate (thickness 1mm).

Other Techniques