Extending the 3ω method for thin-film analysis to high frequencies

Although the 3ω method was originally introduced to measure the thermal conductivity of bulk material and was later developed further to include thin-film materials, many thermal and geometrical parameters influence the 3ω signal. We show that several of these parameters can be determined simultaneously from a single 3ω measurement. With the commonly used frequency range, however, some parameter combinations cannot be determined uniquely. To overcome this problem we have developed an electronic setup for measurements from 5 Hz up to 200 kHz. We show numerically and experimentally that we can determine four physical parameters from a single measurement in this frequency range. This makes the 3ω method very suitable for microelectronics and microsensor testing, where physical parameters should ideally be determined by purely electrical measurements.