Atomic Layer Deposition of Titanium Dioxide Thin Films

Atomic layer deposition (ALD) of titanium dioxide (TiO₂) enables the fabrication of ultrathin, conformal coatings by alternating pulses of a titanium precursor and an oxidant under self-limiting surface reactions. Film growth proceeds cycle by cycle, affording precise control of thickness down to the subnanometre scale and uniform coverage over complex topographies. Depending on the choice of precursor chemistry—commonly tetrakis(dimethylamido)titanium or titanium tetrachloride—and growth temperature (typically 100–300 °C), as-deposited films are amorphous or poorly crystalline. Post-deposition annealing induces phase transformation into anatase or rutile polymorphs, with the transition temperature, crystallite size and phase composition governed by annealing atmosphere, temperature and the concentration of oxygen vacancies or precursor residues. TiO₂ thin films grown by ALD exhibit tunable optical bandgaps (approximately 3.0–3.3 eV), refractive indices between 2.2 and 2.6 (at visible wavelengths), high dielectric constants and excellent chemical stability. Control of point-defect populations, such as oxygen vacancies and Ti³⁺ states, permits fine-tuning of electrical conductivity, charge-carrier lifetimes and visible-light absorption. These attributes underpin a wide array of applications, including photocatalytic water splitting, protective photoelectrodes, antireflective and high-k dielectric coatings, sensors and electron-transport layers in perovskite solar cells. The inherent conformality and thickness precision of ALD thus render it a key enabling technology for integrating TiO₂ thin films into next-generation energy and electronic devices.

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Atomic Layer Deposition of Titanium Dioxide Thin Films publication trend

The graph below shows the total number of articles in atomic layer deposition of titanium dioxide thin films across all publications each year (not limited to Nature Index journals).

Technical terms

Atomic layer deposition (ALD): A thin-film growth technique based on sequential, self-limiting surface reactions that deposit material one atomic layer at a time.

Anatase: A metastable tetragonal polymorph of TiO₂ known for high photocatalytic activity and moderate bandgap energy.

Rutile: The thermodynamically stable tetragonal polymorph of TiO₂, featuring a slightly narrower bandgap and higher refractive index than anatase.

Oxygen vacancy: A point defect formed by the absence of an oxygen atom in the TiO₂ lattice, which introduces electronic states within the bandgap.

Ti³⁺ centre: A reduced titanium ion state commonly generated by oxygen vacancies or reductive treatments, creating mid-gap electronic levels that influence conductivity and optical absorption.

References

1. Production of mixed phase Ti 3+ -rich TiO 2 thin films by oxide defect engineered crystallization. Nanoscale (2024).
2. Improved Stability of Atomic Layer Deposited Amorphous TiO2 Photoelectrode Coatings by Thermally Induced Oxygen Defects. Chemistry of Materials (2018).
3. Structure and photoluminescence of the TiO2 films grown by atomic layer deposition using tetrakis-dimethylamino titanium and ozone. Discover Nano (2015).
4. Optical Constants and Band Gap Evolution with Phase Transition in Sub-20-nm-Thick TiO2 Films Prepared by ALD. Discover Nano (2017).
5. Tunable Ti3+-Mediated Charge Carrier Dynamics of Atomic Layer Deposition-Grown Amorphous TiO2. The Journal of Physical Chemistry C (2022).
6. Low-Temperature Route to Direct Amorphous to Rutile Crystallization of TiO2 Thin Films Grown by Atomic Layer Deposition. The Journal of Physical Chemistry C (2022).
7. Effect of Annealing Temperature on Spatial Atomic Layer Deposited Titanium Oxide and Its Application in Perovskite Solar Cells. Nanomaterials (2020).
8. Mechanical and optical properties of as-grown and thermally annealed titanium dioxide from titanium tetrachloride and water by atomic layer deposition. Thin Solid Films (2021).