Thermoelectric and structural properties of sputtered AZO thin films with varying al doping ratios

Nanomaterials can be game-changers in the arena of sustainable energy production because they may enable highly efficient thermoelectric energy conversion and harvesting. For this purpose, doped thin film oxides have been proven to be promising systems for achieving high thermoelectric performances. In this work, the design, realization, and experimental investigation of the thermo electric properties exhibited by a set of five Al:ZnO thin films with thicknesses of 300 nm and Al doping levels ranging from 2 to 8 at.% are described. Using a multi-technique approach, the main structural and morphological features of the grown thin films are addressed, as well as the electrical and thermoelectrical transport properties. The results show that the samples exhibited a Seebeck coefficient absolute value in the range of 22–33 µV/K, assuming their maximum doping level was 8 at.%, while the samples’ resistivity was decreased below 2 × 10−3 Ohm·cm with a doping level of 3 at.%. The findings shine light on the perspectives of the applications of the metal ZnO thin film technology for thermoelectrics. This research was funded by MIUR-PON, scholarship PhD program “Physics and nano sciences”021/22.“Nanotecnologie per la termoelettricità e l’energy harvesting” (Azione IV.5 “Dottorati su tematiche green”) and by project QUANTEP, INFN CSN5. VB was supported by the project “Brosynano”MICINN-FEDER (PID2019-106820RB-C22). C.T. acknowledges the funding from FCT/PIDDAC through the Strategic Funds project reference UIDB/04650/2020-2023. A.M., G.P. acknowledge support by the Italian Ministry of University and Research through PRIN UTFROM N. 20178PZCB5. This work was also partially funded under the National Recovery and Resilience Plan (NRRP), Mission 04 Component 2 Investment 1.5 – NextGenerationEU, Call for tender n. 3277 dated 30/12/2021. Award Number: 0001052 dated 23/06/2022.