THIN-FILM MICROCALORIMETER FOR HEAT-CAPACITY MEASUREMENTS FROM 1.5-K TO 800-K

A new microcalorimeter for measuring heat capacity of thin films in th e range 1.5-800 K is described. Semiconductor processing techniques ar e used to create a device with an amorphous silicon nitride membrane a s the sample substrate, a Pt thin film resistor for temperatures great er than 40 K, and either a thin film amorphous Nb-Si or a novel boron- doped polycrystalline silicon thermometer for lower temperatures. The addenda of the device, including substrate, is 4X10(-6) J/K at room te mperature and 2X10(-9) J/K at 4.3 K, approximately two orders of magni tude less than any existing calorimeter used for measuring thin films. The device is capable of measuring the heat capacity of thin film sam ples as small as a few micrograms.