Optical and electrical properties of highly doped ZnO:Al films deposited by atomic layer deposition on Si substrates in visible and near infrared region

Optical properties of ZnO films doped by Al in the range 0.5 to 7 at.% and deposited by atomic layer deposition were studied in visible and infrared spectral range. Spectral dependences of film optical permittivity were modeled with the Lorentz-Drude approximation resulting in ZnO:Al plasma frequency and plasma damping parameters. We observed changing electron effective mass from 0.29m₀ to 0.5m₀ with increasing electron concentration in the range (0.9-4) × 10²⁰ due to the phenomenon of conduction band non-parabolicity. Comparing the results of optical and electrical investigations we can see that the main scattering mechanism is the scattering on grain boundaries (its contribution is about 60%).