Molecular layering of 2D films and superlattices based on II–VI compounds

Bisengaliev, R. A.; Novikov, B. V.; Aleskovskii, V. B.; Дрозд, В. Е.; Ageev, D. A.; Gubaidullin, V. I.; Savchenko, A. P.

doi:10.1134/1.1130441

Cited by 4 publications

(1 citation statement)

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“…The prospect of a CdS ALD process based on dimethyl cadmium (DMCd) and H 2 S was demonstrated in the late 90s, , and the first few cycles of CdS growth on ZnSe (100) in ultrahigh vacuum was studied in detail by Luo et al – This work provided a fundamental understanding of the growth mechanism of CdS on ZnSe, and it was suggested that the DMCd exposure etched the substrate with a concomitant release of DMZn species. In spite of the mechanism studies, the CdS growth characteristics have not been systematically investigated until recently, and the mechanistic details of the film growth at steady-state growth have not been reported.…”

Section: Introductionmentioning

confidence: 99%

Molecular Level Insights into Atomic Layer Deposition of CdS by Quantum Chemical Calculations

et al. 2010

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Growth characteristics of cadmium sulfide atomic layer deposition (ALD) from dimethylcadmium (DMCd) and hydrogen sulfide have been investigated by hybrid DFT and MP2 calculations. The steady-state film growth during one ALD cycle was modeled by studying dissociative chemisorption of the dimethylcadmium precursor on the sulfur-terminated (111) surface of zincblende CdS and then by investigating the chemisorption of hydrogen sulfide on the surface formed due to the treatment with the Cd reactant. The calculated reaction barriers for the ALD half reactions suggest that elevated temperatures are required for the film growth. Periodic calculations provide evidence for submonolayer growth per ALD cycle and suggest that steric factors prevent full monolayer formation during DMCd exposure, whereas all adsorption sites are likely to react during the hydrogen sulfide pulse.

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Section: Introductionmentioning

confidence: 99%

Molecular Level Insights into Atomic Layer Deposition of CdS by Quantum Chemical Calculations

et al. 2010

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Surface chemistry of atomic layer deposition: A case study for the trimethylaluminum/water process

Puurunen

2005

Journal of Applied Physics

2,407

2,197

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Atomic layer deposition (ALD), a chemical vapor deposition technique based on sequential self-terminating gas–solid reactions, has for about four decades been applied for manufacturing conformal inorganic material layers with thickness down to the nanometer range. Despite the numerous successful applications of material growth by ALD, many physicochemical processes that control ALD growth are not yet sufficiently understood. To increase understanding of ALD processes, overviews are needed not only of the existing ALD processes and their applications, but also of the knowledge of the surface chemistry of specific ALD processes. This work aims to start the overviews on specific ALD processes by reviewing the experimental information available on the surface chemistry of the trimethylaluminum/water process. This process is generally known as a rather ideal ALD process, and plenty of information is available on its surface chemistry. This in-depth summary of the surface chemistry of one representative ALD process aims also to provide a view on the current status of understanding the surface chemistry of ALD, in general. The review starts by describing the basic characteristics of ALD, discussing the history of ALD—including the question who made the first ALD experiments—and giving an overview of the two-reactant ALD processes investigated to date. Second, the basic concepts related to the surface chemistry of ALD are described from a generic viewpoint applicable to all ALD processes based on compound reactants. This description includes physicochemical requirements for self-terminating reactions, reaction kinetics, typical chemisorption mechanisms, factors causing saturation, reasons for growth of less than a monolayer per cycle, effect of the temperature and number of cycles on the growth per cycle (GPC), and the growth mode. A comparison is made of three models available for estimating the sterically allowed value of GPC in ALD. Third, the experimental information on the surface chemistry in the trimethylaluminum/water ALD process are reviewed using the concepts developed in the second part of this review. The results are reviewed critically, with an aim to combine the information obtained in different types of investigations, such as growth experiments on flat substrates and reaction chemistry investigation on high-surface-area materials. Although the surface chemistry of the trimethylaluminum/water ALD process is rather well understood, systematic investigations of the reaction kinetics and the growth mode on different substrates are still missing. The last part of the review is devoted to discussing issues which may hamper surface chemistry investigations of ALD, such as problematic historical assumptions, nonstandard terminology, and the effect of experimental conditions on the surface chemistry of ALD. I hope that this review can help the newcomer get acquainted with the exciting and challenging field of surface chemistry of ALD and can serve as a useful guide for the specialist towards the fifth decade of ALD research.

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Crystallinity of inorganic films grown by atomic layer deposition: Overview and general trends

Miikkulainen

Leskelä

Ritala

et al. 2013

Journal of Applied Physics

1,300

1,162

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Atomic layer deposition (ALD) is gaining attention as a thin film deposition method, uniquely suitable for depositing uniform and conformal films on complex three-dimensional topographies. The deposition of a film of a given material by ALD relies on the successive, separated, and self-terminating gas–solid reactions of typically two gaseous reactants. Hundreds of ALD chemistries have been found for depositing a variety of materials during the past decades, mostly for inorganic materials but lately also for organic and inorganic–organic hybrid compounds. One factor that often dictates the properties of ALD films in actual applications is the crystallinity of the grown film: Is the material amorphous or, if it is crystalline, which phase(s) is (are) present. In this thematic review, we first describe the basics of ALD, summarize the two-reactant ALD processes to grow inorganic materials developed to-date, updating the information of an earlier review on ALD [R. L. Puurunen, J. Appl. Phys. 97, 121301 (2005)], and give an overview of the status of processing ternary compounds by ALD. We then proceed to analyze the published experimental data for information on the crystallinity and phase of inorganic materials deposited by ALD from different reactants at different temperatures. The data are collected for films in their as-deposited state and tabulated for easy reference. Case studies are presented to illustrate the effect of different process parameters on crystallinity for representative materials: aluminium oxide, zirconium oxide, zinc oxide, titanium nitride, zinc zulfide, and ruthenium. Finally, we discuss the general trends in the development of film crystallinity as function of ALD process parameters. The authors hope that this review will help newcomers to ALD to familiarize themselves with the complex world of crystalline ALD films and, at the same time, serve for the expert as a handbook-type reference source on ALD processes and film crystallinity.

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Molecular layering of 2D films and superlattices based on II–VI compounds

Cited by 4 publications

References 4 publications

Molecular Level Insights into Atomic Layer Deposition of CdS by Quantum Chemical Calculations

Molecular Level Insights into Atomic Layer Deposition of CdS by Quantum Chemical Calculations

Surface chemistry of atomic layer deposition: A case study for the trimethylaluminum/water process

Crystallinity of inorganic films grown by atomic layer deposition: Overview and general trends

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