Thermoelectric and Structural Characterization of Al-Doped ZnO/Y₂O₃ Multilayers.

Area of Science:

• Materials Science
• Nanotechnology
• Thermoelectrics

Background:

• Aluminum-doped zinc oxide (AZO) is a promising material for thermoelectric applications.
• Controlling nanostructure is crucial for optimizing thermoelectric performance.
• Yttrium oxide (Y2O3) nanolayers offer a potential route for defect engineering.

Purpose of the Study:

• To investigate the effect of Y2O3 nanolayers on the thermoelectric properties and structure of AZO thin films.
• To explore the feasibility of using nanoengineered defects to reduce thermal conductivity.
• To optimize the thermoelectric figure of merit (ZT) in AZO-based multilayers.

Main Methods:

• Multilayer thin films of AZO and Y2O3 were fabricated using pulsed laser deposition.
• Alternate ablation of AZO and Y2O3 targets on Al2O3 single crystals.
• Varied the number of laser pulses on the Y2O3 target (5, 10, 15) to control nanolayer thickness.

Main Results:

• The AZO phase maintained its polycrystalline and columnar structure, unaffected by Y2O3 nanolayers.
• The multilayer with 15 Y2O3 laser pulses exhibited the best thermoelectric performance.
• Achieved electrical conductivity of 48 S/cm and Seebeck coefficient of -82 μV/K at 600 K.
• Observed a significant reduction in thermal conductivity to 10.03 W m−1 K−1 at 300 K (one-third of bulk AZO).
• Calculated a figure of merit (ZT) of 9.6 × 10−4 at 600 K.

Conclusions:

• Nanoengineered insertion of Y2O3 defects effectively suppresses thermal conductivity in AZO thin films.
• The developed multilayer structure demonstrates enhanced thermoelectric performance.
• This study highlights the potential of nanostructuring for improving thermoelectric materials.