Thermoelectric Properties of Zinc-Doped Indium Tin Oxide Thin Films Prepared Using the Magnetron Co-Sputtering Method

Abstract

The thermoelectric properties of In−Sn−O (ITO) thin films were estimated in relation to microstructures with various zinc concentrations. The zinc-doped ITO (ITO:Zn) thin films were amorphized with increasing zinc concentration. The carrier density (n) of the thin films decreased as the zinc content increased, which could be attributed to a decline in oxygen vacancies. The highest Seebeck coefficient (S, 64.91 μV/K) was obtained with an ITO film containing 15.33 at.% of Zn due to the low n value, which also exhibited the highest power factor (234.03 μW K−2 m−1). However, the highest thermoelectric figure of merit value (0.0627) was obtained from the film containing 18.26 at.% of Zn because of both low n and the lowest thermal conductivity (κ) (1.085 W m−1·K−1). The total κ decreased as increasing zinc concentration in the thin films. It was confirmed that the decrease of total κ was dominated by electron κ rather than lattice κ.

Embedded Nanopattern for Selectively Suppressed Thermal Conductivity and Enhanced Transparency in a Transparent Conducting Oxide Film

“…Fig. 5c compiles reported figure of merit, FoM, values (ZT and ϕ TC ) for transparent conductive materials published the past 5 years [22,27,28,[46][47][48][49][50][51][52][53][54][55][56]. Red circles and blue triangles represent n-type and p-type materials, respectively.…”

“…Indium tin oxide (ITO) has been intensively studied in the past, mainly as a TCO material [26], but also regarding its TE properties [27,28]. Despite the outstanding optical and electrical properties of ITO, it is difficult to obtain ITO-based films that exhibit adequate electronic, optical and thermal properties simultaneously.…”

“…This is because, as discussed above, larger n values result in lower ZT. We have previously reported that an ITO thin film with an amorphous structure can exhibit fairly high σ without an accompanying increase of n and still have low κ l because of high carrier mobility due to non-directional In 5 s bonding with oxygen [27,28]. However, amorphous thin films have relatively poor electrical conductivity compared to crystalline oxide TE materials, which is an inherent limitation of amorphous metal oxides [26,34,35].…”

Multifunctional Zn-Doped ITO Sol–Gel Films Deposited on Different Substrates: Application as CO2-Sensing Material

“…The Zn-doped ITO (ITO:Zn) films reported so far in the literature were deposited using physical methods, especially magnetron sputtering on glass substrate [52], quartz [53], and plastic foils [44,54]. A more recent paper presented the thermoelectric properties of Zn-doped ITO thin films with various Zn concentrations prepared using the magnetron co-sputtering method [55]. Accordingly, there are very few published papers concerning Zn-doped ITO thin films prepared using sol-gel methods [56,57].…”

Controlled Lattice Thermal Conductivity of Transparent Conductive Oxide Thin Film via Localized Vibration of Doping Atoms

“…In our previous study, the microstructure of the ITO thin film was manipulated to control n and thermal conductivity without reducing the electrical conductivity of the thin film by doping with ZnO [ 24 ]. The total thermal conductivity ( κ tot ) decreased with the increase in the ZnO concentration.…”