Structure function analysis of temperature-dependent thermal properties of Nm-thin Nb 2 O 5

Abstract

A 166-nm-thick amorphous Niobium pentoxide layer (Nb 2 O 5 ) on a silicon substrate was investigated by using time domain thermoreflectance at ambient temperatures from 25 ◦ C to 500 ◦ C. In the time domain thermoreflectance measurements, thermal transients with a time resolution in (sub-)nanoseconds can be obtained by a pump-probe laser technique. The analysis of the thermal transient was carried out via the established analytical approach, but also by a numerical approach. The analytical approach showed a thermal diffusivity and thermal conductivity from 0.43 mm 2 /s to 0.74 mm 2 /s and from 1.0 W/mK to 2.3 W/mK, respectively to temperature. The used numerical approach was the structure function approach to map the measured heat path in terms of a R th C th -network. The structure function showed a decrease of R th with increasing temperature according to the increasing thermal conductivity of Nb 2 O 5 . The combination of both approaches contributes to an in-depth thermal analysis of Nb 2 O 5 film.