Plasma enhanced atomic layer deposition of zinc sulfide thin films

Kuhs, Jakob; Dobbelaere, Thomas; Hens, Zeger; Detavernier, Christophe

doi:10.1116/1.4967724

Cited by 23 publications

(15 citation statements)

References 33 publications

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“…Similar oxygen enrichment has been reported in other ALD or PEALD processes of Al 2 S 3 , where even the use of O-free precursors and/or the protection with a ZnS capping layer does not prevent the O contamination. 40,47,48 A Cu−S/Al−O gradient in depth (Cu−S toward the surface, Al−O toward the substrate) is visible, especially for the 2:5 film. The linearity of its tendency, the gradual shift of the photopeaks toward higher BE, and the hardness of the layer are explained by the progressive increase of the insulating character in depth.…”

Section: Discussionmentioning

confidence: 99%

Transparent Ohmic Contact for CIGS Solar Cells Based on p-Type Aluminum Copper Sulfide Material Synthesized by Atomic Layer Deposition

Schneider

Duclaux

Bouttemy

et al. 2018

ACS Appl. Energy Mater.

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A p-type transparent conducting material was developed to be used as transparent back-contact for the next generation of Cu(In,Ga)Se 2 (CIGS) based solar cells. Cu−S:Al−S thin films were synthesized by atomic layer deposition at temperature T dep = 150 °C, by combining Cu x S and Al 2 S 3 cycles obtained from copper acetylacetonate (Cu(acac) 2 ), trimethylaluminum (TMA), and hydrogen sulfide (H 2 S). Thin films were characterized notably by X-ray diffraction, scanning electron microscopy, and UV−vis spectrophotometry. This synthesis strategy allowed a tuning of the film compositions and optoelectronic properties. Films have a high oxygen content, and their growth mechanisms as well as their fine chemistries were explored by X-ray photoelectron spectroscopy chemical profiling studies. The layers appeared as intermixed copper sulfide and aluminum oxide networks with some Cu−O and Al−S chemical bonds. Finally, best candidates were successfully applied as transparent ohmic contacts with CIGS with contact resistance between 0.1 and 0.7 Ω•cm −2 .

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Section: Discussionmentioning

confidence: 99%

Transparent Ohmic Contact for CIGS Solar Cells Based on p-Type Aluminum Copper Sulfide Material Synthesized by Atomic Layer Deposition

Schneider

Duclaux

Bouttemy

et al. 2018

ACS Appl. Energy Mater.

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“…To investigate the potential of in situ photoluminescence measurements during gas exposure and ALD growth, we redesigned an already existing H 2 S compatible, home-built pump-type ALD reactor . A schematic overview of the ALD system can be found in Figure .…”

Section: Methodsmentioning

confidence: 99%

In Situ Photoluminescence of Colloidal Quantum Dots During Gas Exposure—The Role of Water and Reactive Atomic Layer Deposition Precursors

Kuhs

Werbrouck

Zawacka

et al. 2019

ACS Appl. Mater. Interfaces

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Colloidal quantum dots (QDs) are a promising material for optoelectronic applications. Typically, device integration requires QDs to be embedded in a host material. Atomic layer deposition (ALD) is often considered as a deposition technique for such purposes. However, it is known that ALD and vacuum processes often influence the optical properties of QDs in a negative way. Here, we describe an in situ photoluminescence (PL) measurement setup and use it to monitor the PL of QDs under vacuum and during ALD. For CdSe-based core/shell QDs, a reduction in the QD PL was observed upon exposure to vacuum. Water was identified as crucial for maintaining a high PL as evidenced by re-exposure to different gases. Furthermore, we addressed the influence of vacuum, different plasmas (O 2 , H 2 O, H 2 , H 2 S/Ar, and Ar), precursors (trimethylaluminum, diethylzinc, tetrakis(dimethylamido)titanium, and tetrakis(ethylmethylamido)hafnium), reactants (H 2 O, H 2 S, and O 3 ), and ALD processes (Al 2 O 3 , TiO 2 , HfO 2 , and ZnS) on QDs. We observed a PL reduction by up to 90% upon plasma treatments. Furthermore, we found that trimethylaluminum and diethylzinc reduced the PL efficiency by more than 70% while exposure to tetrakis(dimethylamido)titanium and tetrakis(ethylmethylamido)hafnium lowered the PL by only 10−20%. Surprisingly, tetrakis(dimethylamido)titanium and H 2 O, which by themselves had only a minor influence on the QD PL, still caused an 80% drop of the PL efficiency when combined as an ALD process. On the other hand, ALD growth of HfO 2 by combining tetrakis(ethylmethylamido)hafnium and O 3 preserved 80% of the initial PL quantum yield, making it a promising process for QD embedding. These results put forward in situ PL measurements as a versatile technique to identify suitable precursors, reactants and ALD processes for QD embedding and investigate the interaction between QDs and reactive gaseous species in general.

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“…GaS x thin films were deposited in a home-built pump-type ALD reactor which was redesigned to be compatible with hydrogen sulfide following the suggestions described by Dasgupta et al 27 A detailed description of the used ALD system can be found in our previous work. 25,26 GaS x thin films were deposited by using TMG (.99%, Strem) as precursor. As a reactant pure H 2 S gas (for thermal ALD experiments) or H 2 S plasma diluted by Ar (1:3) (for PE-ALD experiments) was used.…”

Section: Methodsmentioning

confidence: 99%

“…In previous studies, we investigated the optical emission spectrum of H 2 S plasma. 25,26 These studies revealed the presence of H þ and S þ ions. Furthermore, H 2 S þ radicals were detected while no optical emission from the metals involved in the ALD process was found.…”

Section: B Reaction Mechanismmentioning

confidence: 95%

“…21 Recently, the use of H 2 S plasma instead of H 2 S opened the possibility for new ALD processes. [24][25][26] Especially, our previous results on plasma enhanced ALD (PE-ALD) of Al 2 S 3 are very promising for GaS x ALD. 26 The observation that thermal ALD of trimethylaluminum (TMA) þ H 2 S did not result in any growth while an ALD process could be established in combination with H 2 S plasma motivated us to try a similar approach for GaS x combining TMG with H 2 S plasma.…”

Section: Introductionmentioning

confidence: 91%

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Plasma enhanced atomic layer deposition of gallium sulfide thin films

Kuhs

Hens

Detavernier

2019

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Gallium sulfide has a great potential for optoelectronic and energy storage applications. Since most of these applications require a high control over the layer thickness or a high conformality, atomic layer deposition is a promising deposition technique. In this work, the authors present a novel plasma enhanced atomic layer deposition process for gallium sulfide based on trimethylgallium and H 2 S/Ar plasma. The growth was characterized using in situ spectroscopic ellipsometry. It was found that the process grew linearly at a rate of 0.65 Å/cycle and was self-limited in the temperature range from 70 to 350°C. The process relied on a combustion reaction, which was shown by the presence of CS 2 during in situ mass spectrometry measurements. Furthermore, the material properties were investigated by x-ray photoelectron spectroscopy, x-ray diffraction, and optical transmission measurements. The as-deposited films were amorphous and pinhole free. The GaS x thin films had a transmittance of .90% and a band gap of 3.1-3.3 eV.

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Plasma enhanced atomic layer deposition of zinc sulfide thin films

Cited by 23 publications

References 33 publications

Transparent Ohmic Contact for CIGS Solar Cells Based on p-Type Aluminum Copper Sulfide Material Synthesized by Atomic Layer Deposition

Transparent Ohmic Contact for CIGS Solar Cells Based on p-Type Aluminum Copper Sulfide Material Synthesized by Atomic Layer Deposition

In Situ Photoluminescence of Colloidal Quantum Dots During Gas Exposure—The Role of Water and Reactive Atomic Layer Deposition Precursors

Plasma enhanced atomic layer deposition of gallium sulfide thin films

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