Substrate dependence on the optical properties of Al2O3 films grown by atomic layer deposition

The atomic layer deposition technique has been applied to the growth of Al2O3 thin films on the substrates of Si(100), 100-nm-thick SiO2 covered Si(100) [SiO2/Si(100)], and 90-nm-thick TiN covered SiO2/Si(100). The growth rate of Al2O3 films was 0.19 nm/cycle and identical for all substrates employed under the surface controlled process. However, the optical properties of Al2O3 films were significantly affected by different substrates. The average interband-oscillator energy and refractive index parameter were determined to be 3.330 eV and 2.992×10−14 eV m2 for Al2O3 film grown on Si(100), while those for the film grown on SiO2/Si(100) were 4.492 eV and 2.074×10−14 eV m2, respectively.