Control of p-type conduction in Mg doped monophase CuCrO₂thin layers

Thermoelectric and Transport Properties of Delafossite CuCrO2:Mg Thin Films Prepared by RF Magnetron Sputtering

“…Consequently the Jonker plot S versus ln( σ ) [96] showed a degenerate semiconductor behavior for the whole samples. Chikoidze et al [83] noticed the quasi invariance of the Seebeck coefficient with the measurement temperature, which is consistent with the present results. Farrell et al [72] also reported degenerate behavior for Cu deficient CuCrO 2 film.…”

“…The obtained energy value is consistent with the literature [84] and shows a wide band gap which avoids the simultaneous presence of the electron and hole in their specific bands and drives to a high Seebeck coefficient even at high temperatures. A similar indirect band gap value was obtained by Chikoidze et al [83] and Kaya et al [99]. …”

“…Similar decrease of the electrical conductivity has already been observed by various authors and attributed to the decrease of copper vacancies and oxygen interstitials at higher temperatures [75,88] or microstructural changes [16]. In the literature, the electrical conductivity of CuCrO 2 :Mg films ranged from 0.033 to 1.6 S·cm −1 [16,78,83,84,89,90]. For 305 nm thick CuCrO 2 :Mg films, Rastogi et al [84] found 0.1–0.2 S·cm −1 whereas, higher electrical conductivity of 0.6–1 S·cm −1 was obtained for 155 nm thick films.…”

“…Tripathi et al [82] reported comparable value (≃+300 µV·K −1 at room temperature) for undoped CuCrO 2 films. On the other hand, Chikoidze et al [83] published three times lower value of Seebeck coefficient (+130 µV·K −1 at 23 °C) for 4% Mg doped CuCrO 2 thin film. Overall, trends are similar and the difference in values could be explained by the difference in the measurement setup and the material type.…”

“…In comparison with CuCrO 2 and CuCrO 2 :Mg studies carried out on bulk materials [70,71,74,79,80], there is a lack of papers related to proper studies of the TE properties of CuCrO 2 :Mg thin films, as for instance, the determination of PF . Most of the time, Seebeck measurements presented in the bibliography are only used to characterize the fundamental physical properties (type of charge carriers, transport mechanism) [16,73,81,82,83,84,85] especially because it is difficult to determine the main charge carrier characteristics by conventional Hall measurements in this type of material. In particular, we have measured the Seebeck coefficient at room temperature for 100 nm thick films in order to determine the type of the main charge carrier in CuCrO 2 :Mg thin films optimized for TCO properties [16].…”