Structural, Optical, and Thermoelectric Properties of the ZnO:Al Films Synthesized by Atomic Layer Deposition

• Published in: Physics of the solid state 2019-10, Vol.61 (10), p.1904-1909
• Main Authors: Tambasov, I. A., Volochaev, M. N., Voronin, A. S., Evsevskaya, N. P., Masyugin, A. N., Aleksandrovskii, A. S., Smolyarova, T. E., Nemtsev, I. V., Lyashchenko, S. A., Bondarenko, G. N., Tambasova, E. V.
• Format: Article
• Language: English
• Subjects: ABSORPTION; Absorptivity; ALUMINIUM; ALUMINIUM OXIDES; Aluminum; Aluminum oxide; Atomic layer epitaxy; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; DEPOSITION; Dielectric films; Diffraction; DOPED MATERIALS; Electric properties; ELECTRON DIFFRACTION; Hexagonal phase; Maximum power; Optical properties; Photovoltaic cells; Physics; Physics and Astronomy; Physics of Surface and Thin Films; Planes; POWER FACTOR; REFLECTION; REFRACTIVE INDEX; Refractivity; ROUGHNESS; Seebeck effect; Solid State Physics; Substrates; TEMPERATURE RANGE 0273-0400 K; THERMOELECTRIC PROPERTIES; Thermoelectricity; THIN FILMS; TRANSMISSION; WAVELENGTHS; X-RAY DIFFRACTION; X-rays; Zinc oxide; ZINC OXIDES
• ISSN: 1063-7834; 1090-6460
• DOI: 10.1134/S1063783419100354

Aluminum-doped zinc oxide thin films have been grown by atomic layer deposition at a temperature of 200°C. Using X-ray diffraction, it has been established that the ZnO:Al thin films exhibits the reflections from the (100), (002), (110), and (201) ZnO hexagonal phase planes. The (101) and (102) planes have also been detected by electron diffraction. The ZnO:Al thin films grow smooth with a root-mean-square roughness of R q = 0.33 nm and characteristic nanocrystallite sizes of ~70 and ~15 nm without additional aluminum or aluminum oxide phases. The transmission at a wavelength of 550 nm with regard to the substrate has been found to be 96%. The refractive indices and absorption coefficients of the ZnO:Al thin films in the wavelength range of 250–900 nm have been determined. The maximum refractive indices and absorption coefficients have been found to be 2.09 at a wavelength of 335 nm and 0.39 at a wavelength of 295 nm, respectively. The optical band gap is 3.56 eV. The resistivity, Seebeck coefficient, and power factor of the ZnO:Al thin films are ∼1.02 × 10 –3 Ω cm, –60 μV/K, and 340 μW m –1 K –2 at room temperature, respectively. The maximum power factor attains 620 μW m –1 K –2 at a temperature of 200°C.