Atomic Layer Deposition in Chalcogenides

ALD Applications

Chalcogenide materials consist of at least one chalcogen anion (group 16 element), in particular sulfide, selenide, and telluride, shown in red. The transition metals chalcogenides consist of a transition metal (d-block elements) bonded with a chalcogenide (S, Se, Te). These materials exhibit unique material properties and are highly covalent, exhibiting semiconducting properties.
Transition metal dichalcogenides (TMD) include metals that form a metal disulfide (MS2), metal diselenide (MSe2), or metal ditelluride (MTe2). TMD materials of particular interest in recent research are shown in green on the periodic table.

APPLICATIONS

Atomic layer deposition techniques can be used to deposit thin film chalcogenide materials, either directly, or by utilizing a sulfurization anneal after the ALD deposition. ALD techniques offer unique capabilities to deposit films on three dimensional features in a conformal manner with accurate material composition and  controlled film thickness.
There has been a pronounced interest in transition metal chalcogenide materials for photovoltaics, photonics, catalysis, and energy storage applications. Of particular interest have been the sulfide chalcogenide materials.

Examples of chalcogenide films deposited on CNT platforms

ZnS – Zn(1-x)OxS  -  CoS
In2S3 – PbS – Sb2S3
Cu2S – Cu2ZnSnS4

Single junction efficiency limits

ALD sulfide absorbers

Ref: Dasgupta, N. P., et al., Accounts Chem Res 48, 341–348 (2015).


CHALCOGENIDE PHOTOVOLTAICS

Atomic layer deposition techniques can be used to deposit thin film chalcogenide materials.

Chalcogenide materials for photovoltaics applications have been explored for the absorber materials where bandgap energies are better suited to achieve higher levels of efficiency ( 31 - 34% efficiency at 1-1.6 eV). Quaternary films can be deposited using ALD techniques, including copper zinc tin sulfide (CZTS). ALD deposited materials can also be used for fabricated buffer / emitter materials (In2S3, ZnS, CdS, and Zn(O,S)).


ENERGY STORAGE

ALD deposited films have been investigated in energy storage and battery applications with demonstrated levels of improved performance.

    • Cu2S / carbon nano-tubes (CNT) cathodes @260 mA h g-1
    • Li2S @ 800 mA h g-1

PHOTONICS

Chalcogenide materials have also been used in the photonic and solar applications.
ZnS for TFEL displays (first ALD industrial application)


2D DICHALCOGENIDES

Two dimension dichalcogenides have been investigated for their unique material properties, including band gap semi conducting properties, photoluminescence, and absorbance as the film thickness is reduced to one monolayer thickness.  Atomic layer deposition offers a direct method toward achieving a one molecular layer thick film. Research is actively being pursued to develop a two step process utilizing ALD and a sulfurization anneal, or a direct growth method for transition metal dichalcogenide (TMD) materials.
ZnS for TFEL displays (first ALD industrial application)

Cu2S / SnS2 / ZnS trilayer deposited on a silicon trench wafer

Ref: Thimsen et al. , Chemistry of Materials, 24(16), 3188–3196 (2012)

REFERENCES – Recent publications done on Veeco CNT ALD platforms

  1. Xu, J. et al. Atomic layer deposition of absorbing thin films on nanostructured electrodes for short-wavelength infrared photosensing. Appl Phys Lett 107, 153105–5 (2015).
  2. McCarthy, R. F., Schaller, R. D., Gosztola, D. J., Wiederrecht, G. P. & Martinson, A. B. F. Photoexcited Carrier Dynamics of In2S3 Thin Films. J. Phys. Chem. Lett. (2015). doi:10.1021/acs.jpclett.5b00935
  3. Baryshev, S. V., Riha, S. C. & Zinovev, A. V. Solar Absorber Cu2ZnSnS4 and its Parent Multilayers ZnS/SnS2/Cu2S Synthesized by Atomic Layer Deposition and Analyzed by X-ray Photoelectron Spectroscopy. Surf. Sci. Spectra 22, 81–99 (2015).
  4. Riha, S. C., Schaller, R. D., Gosztola, D. J., Wiederrecht, G. P. & Martinson, A. B. F. Photoexcited Carrier Dynamics of Cu 2S Thin Films. J. Phys. Chem. Lett. 5, 4055–4061 (2014).
  5. Sutherland, B. R. et al. Perovskite Thin Films via Atomic Layer Deposition. Advanced Materials n/a–n/a (2014). doi:10.1002/adma.201403965
  6. McCarthy, R. F., Weimer, M. S., Emery, J. D., Hock, A. S. & Martinson, A. B. F. Oxygen-Free Atomic Layer Deposition of Indium Sulfide. Acs Appl Mater Inter 6, 12137–12145 (2014).
  7. Riha, S. C. et al. Stabilizing Cu 2S for Photovoltaics One Atomic Layer at a Time. Acs Appl Mater Inter 131010083550003 (2013). doi:10.1021/am403225e
  8. Thimsen, E. et al. Interfaces and Composition Profiles in Metal–Sulfide Nanolayers Synthesized by Atomic Layer Deposition. Chem Mater 25, 313–319 (2013).
  9. Thimsen, E. et al. Atomic Layer Deposition of the Quaternary Chalcogenide Cu 2ZnSnS 4. Chem Mater 24, 3188– 3196 (2012).
  10. Yang, R. B. et al. Pulsed Vapor-Liquid-Solid Growth of Antimony Selenide and Antimony Sulfide Nanowires. Advanced Materials 21, 3170–3174 (2009).
  11. Dasgupta, N. P., Walch, S. P. & Prinz, F. Fabrication and Characterization of Lead Sulfide Thin Films by Atomic Layer Deposition. ECS Transactions 16, 29–36 (2008).