Characterization of dielectric layers grown at low temperature by atomic layer deposition

Dielectric films, such as hafnium dioxide (HfO₂), aluminum oxide (Al₂O₃), zirconium dioxide (ZrO₂), titanium dioxide (TiO₂) and their composite layers are deposited on polycrystalline and amorphous substrates by the atomic layer deposition (ALD) method. We demonstrate that the use of this technology guarantees a uniform and controlled surface coverage in the nanometer scale at low temperatures (in our case, below 100 °C). Modification of the composition of oxide layers allows the deposition of materials with quite different absorption coefficients, refractive indexes and dielectric constants. In particular, we demonstrate structural, electrical and optical properties of dielectric layers and test metal-oxide-semiconductor structures with these oxide materials. Our good quality dielectric layers, obtained at low-temperature ALD, are characterized by a high dielectric constant (above 10), very smooth surface, wide energy gap (above 3 eV), low leakage current (in the range of 10⁻⁸ A/cm² at 1 V), high dielectric strength (even 6 MV/cm) and high refractive indexes (above 1.5 in the visible spectral range). - Highlights: • We demonstrate the use of atomic layer deposition (ALD) at low temperatures (LT). • LT ALD guarantees a uniform and controlled surface coverage of dielectrics. • In our case, the dielectric films were deposited at very LT, below 100 °C. • Dielectrics (HfO₂, Al₂O₃, ZrO₂, TiO₂ and composite layers) are obtained by ALD. • Our results also indicate high-quality dielectric films