The Seebeck Coefficient of Sputter Deposited Metallic Thin Films: The Role of Process Conditions

Abstract

Because of their reduced dimensions and mass, thin film thermocouples are a promising candidate for embedded sensors in composite materials, especially for application in lightweight and smart structures. The sensitivity of the thin film thermocouple depends however on the process conditions during deposition. In this work, the influence of the discharge current and residual gas impurities on the Seebeck coefficient is experimentally investigated for sputter deposited copper and constantan thin films. The influence of the layer thickness on the film Seebeck coefficient is also discussed. Our observations indicate that both a decreasing discharge current or an increasing background pressure results in a growing deviation of the film Seebeck coefficient compared to its bulk value. Variations in discharge current or background pressure are linked as they both induce a variation in the ratio between the impurity flux to metal flux towards the growing film. This latter parameter is considered a quantitative measure for the background residual gas incorporation in the film and is known to act as a grain refiner. The observed results emphasize the importance of the domain size on the Seebeck coefficient of metallic thin films.

Magnetic and Electronic Properties of Weyl Semimetal Co2MnGa Thin Films

“…Further, the improved crystallinity inferred from rocking curve measurements [ 34 ] indicates that the overall film quality increases with increasing film thickness. Similar behavior can also be observed in other thin films [ 51 , 52 ]. Table 1 summarizes the values of S q and D .…”

Sputter Deposited Metal Layers Embedded in Composites—From Fundamentals to Applications

“…This power law behavior was also illustrated for the resistivity of constantan (Cu 55 Ni 45 and chromel (Ni 90 Cr 10 ) thin films [35]. The same behavior is observed for the Seebeck coefficient as shown in Figure 7 (left) [16]. To increase the impurity pressure, air was leaked into the chamber.…”

“…Finally, the aforementioned prepreg plies were also used as substrate. The procedure to deposit thermocouples is described in [16].…”

Optically-Thin Broadband Graphene-Membrane Photodetector

“…Hence, optical absorption affects conductivity, which is a considerably stronger effect than the Seebeck mechanism, which generates low photo-voltage ∆V = S∇T even for the large Seebeck constant S of graphene [36]. The gradient thickness of metal contact used in this study can be also useful for measurement of the Seebeck constant of metal nanofilms, where it depends on the mean free path of electrons and phonon drag [37,38], and has to be experimentally determined for precise temperature measurements at the nanoscale [39].…”