Materials - Aluminium oxide layers

Aluminium oxide layers


Aluminium oxide, also known as alumina (Al2O3), thin flims are obtained by atomic layer deposition (ALD) on range of substrates, like Si, GaN, SiC, graphene, SiO2 etc. The material is formed in a double exchange chemical reaction between two reactants (precursors), such as a deionized water (oxygen precursor) and a trimetylaluminum - TMA (aluminium precursor). Al2O3 can be grown at the temperature range from 25°C to 300°C. The maximum size of the substrate is 20 cm of a diameter.



  • Thickness: 10 - 3000 nm
  • Growth rate: 0.2 nm/minute
  • Resistivity: > 108 Ωcm
  • Energy gap: 6.3 eV
  • Refractive index: 1.6 (635 nm)
  • Relative permittivity: 10±3
  • Surface roughness: 0.2 nm < RMS < 5 nm
  • Structure: amorphous layers
  • Average transmission in visible spectra:> 80%
  • Uniformity of coatings



Al2O3, due to its  good optical, electrical and structural properties,  can be used as an insulator in electronic devices, especially in "transparent electronics", as optical coatings with high refractive index in lasers and microscopes and as a protective or barrier layers of photovoltaic structures. In addition, this material can be used in medicine and dentistry for the manufacture of prostheses and implants.

Uniformity of zinc oxide layer deposited on 20 cm diameter silicon substrate.

Cross-section image of Al2O3 on silicon substrate from scanning electron microscope (SEM).

Al2O3 surface image (with RMS: 0.2 nm) on silicon substrate from atomic force microscope (AFM).