Deposition of Organic- Inorganic Hybrid Materials by Atomic Layer Deposition

Nilsen, Ola; Klepper, Karina Barnholt; Nielsen, Heidi; Fjellvaag, H.

doi:10.1149/1.2979975

Cited by 81 publications

(93 citation statements)

References 17 publications

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“…The results can be largely correlated to some previous reports. The MLD process using TMA and 4‐hydroquinone was successfully performed and studied at low temperatures . However, only one publication described the MLD process involving TMA and 4‐phenylenediamine, which works at 400 °C.…”

Section: Discussionmentioning

confidence: 99%

Reversible and Irreversible Reactions of Trimethylaluminum with Common Organic Functional Groups as a Model for Molecular Layer Deposition and Vapor Phase Infiltration

Yang

Brede²,

Ablat

et al. 2017

Adv Materials Inter

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Organic–inorganic hybrid materials are of great demand not at least for their enormous application potential in flexible devices. Atomic or molecular layer deposition (ALD or MLD) and vapor phase infiltration (VPI) offer novel pathways for the fabrication of such hybrids, but a clear understanding of the chemistry between the vaporized precursors and functional molecules is still lacking. In this work, the interactions between trimethylaluminum (TMA) and the organic functional groups OH, NH2, and NO2 in the respective substituted phenyls, as well as their stability upon exposure to air are investigated. The experimental evidence agrees with theoretically predicted reaction pathways, showing that TMA initially binds to Lewis basic atoms of the investigated functional groups. Depending on the reaction energy barriers, the interaction between TMA and the investigated functional groups may result in either stable chemical bonding or intermediates that decompose upon exposure to humidity. This investigation contributes to the understanding of ALD/MLD and VPI processes at a molecular level and will support a better process optimization.

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Section: Discussionmentioning

confidence: 99%

Reversible and Irreversible Reactions of Trimethylaluminum with Common Organic Functional Groups as a Model for Molecular Layer Deposition and Vapor Phase Infiltration

Yang

Brede²,

Ablat

et al. 2017

Adv Materials Inter

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“…[24,25] In combination with the ALD fabrication of inorganic materials, a very convenient and highly controllable route to nanostructuring is molecular layer deposition (MLD) to produce hybrid inorganic-organic materials (Figure 1d). [26][27][28][29][30][31][32] The combined ALD/MLD technique has been used to fabricate various nanoscale oxide-organic superlattices in a highly controllable fashion [33] and crystalline ZnO-organic superlattices fabricated using hydroquinone (HQ, benzene-1,4-diol, HOC 6 H 4 OH) as the organic precursor indeed show orderof-magnitude reduction of thermal conductivity. [34] The orderof-magnitude reduction of thermal conductivity has also been proven for analogous hybrid TiO 2 -organic superlattices fabricated by ALD/MLD, highlighting the wider applicability of the oxide-organic superlattice approach for the thermal engineering of metal oxides.…”

Section: Wileyonlinelibrarycommentioning

confidence: 99%

Flexible Thermoelectric ZnO–Organic Superlattices on Cotton Textile Substrates by ALD/MLD

Karttunen

Sarnes

Townsend

et al. 2017

Adv Elect Materials

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we focus on small-scale energy harvesting based on the thermoelectric effect.Thermoelectric materials can be used to convert waste heat to electric energy via Seebeck effect. They are characterized by a dimensionless figure-of-merit ZT = S 2 σT/(κ e + κ L ), where S is the Seebeck coefficient (thermopower), σ the electrical conductivity, T the temperature, and κ e and κ L the electronic and lattice contributions to the thermal conductivity κ. [12] Figure 1 illustrates the basic principle of a conventional thermoelectric (TE) energy conversion device and the concept of a TE generator device combined with a flexible substrate. Furthermore, Figure 1c shows how the ZT value arises from the abovementioned individual components. Alloys of bismuth telluride (Bi 2 Te 3 ) and antimony telluride (Sb 2 Te 3 ) are by far the most widely used TE materials. They show high ZT values for near-room-temperature applications and have been utilized for decades in solid-state refrigeration applications. A major obstacle for the widespread utilization of Bi-Sb-Te based thermoelectrics is the low abundance of tellurium: it is among the rarest elements in the Earth's crust. Furthermore, current thermoelectric generators based on conventional TE materials such as Bi 2 Te 3 are typically inflexible solid-state devices, which would not be convenient for mobile small-scale applications. [12] Consequently, there is a significant interest in producing flexible and efficient TE generator solutions. In particular, a mechanically flexible TE generator solution integrated with light-weight and comfortable textile substrates could be an enabling platform for body-heat-based energy harvesting.Recently Lee et al. fabricated woven-yarn thermoelectric textiles by coating electrospun polyacrylonitrile nanofiber cores with n-type Bi 2 Te 3 and p-type Sb 2 Te 3 and twisting them into flexible yarns. [13] By weaving the TE-coated yarns into textiles, they were able to obtain an output power of up to 8.56 W m −2 for a temperature difference of 200 K in the textile thickness direction. Another recent study on thermoelectric fabrics utilized a completely different type of material solution, where thermoelectric PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) polymer was used to coat a polyester fabric with a solution-based method. [14] This fabric-TE device was based on p-type PEDOT:PSS only, resulting in a so-called unileg-type device that produced an output power of about 260 µW m −2 for a temperature difference of 75 K.The thermoelectric properties of both pristine ZnO and ZnO-organic superlattice thin films deposited on a cotton textile are investigated. The thin films are fabricated by atomic layer deposition/molecular layer deposition, using hydroquinone as the organic precursor for the superlattices. The resulting thin-film coatings are crystalline, in particular when deposited on a textile substrate with a thin predeposited Al 2 O 3 seed layer. The thermoelectric properties of the ZnO and ZnO-organic superlattice coatings are comp...

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“…In the present work, we investigate the impact of regular versus irregular/disordered layer arrangements in inorganic–organic hybrid thin films taking the advantage of the ALD/MLD technique for layer engineering. The ALD/MLD technique is uniquely suited for engineering these types of carefully designed structures, because its self‐limiting gas‐surface reactions enable atomic/molecular level film growth control . We chose the ZnO/benzene system as our model system because (i) in ZnO heat conduction is dominated by phonons rather than by charge carriers, (ii) the ALD/MLD process for ZnO/benzene thin films is already established allowing the fabrication of the films in a highly controlled manner, and (iii) in these superlattices the phonon mean free path is of the relevant length .…”

Section: Introductionmentioning

confidence: 99%

Thermal Conductivity Reduction at Inorganic–Organic Interfaces: From Regular Superlattices to Irregular Gradient Layer Sequences

Krahl

Giri

Tomko

et al. 2018

Adv Materials Inter

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been made by introducing disorder in the systems via alloying, complex crystal-engineering, [4,5] and by creating interfaces in thin films. [2] Hicks and Dresselhaus originally proposed that quantum well structures should be capable of lowering the thermal conductivity with only a minor impact on the electrical conductivity; [6] note that the latter point is particularly important for the application in thermoelectrics. Experimentally the phenomenon has been demonstrated, e.g., by Hicks et al. [7] in the PbTe/(Pb,Eu)Te system and by Ohta et al. [8] in the SrTiO 3 /Sr(Ti,Nb)O 3 system. Layered structures that show reduced thermal conductivity have been reported for a number of other material systems as well, such as CaTiO 3 /SrTiO 3 , [9] W/ Al 2 O 3 , [10] PbTe/PbSe, [11] IrSb 3 /CoSb 3 , [12] AlN/GaN, [13] TiNiSn/ HfNiSn, [14] Si/Ge (including alloy variants), [15][16][17][18][19] GaAs/AlAs (including alloy variants), [20][21][22][23] Bi 2 Te 3 /Sb 2 Te 3 , [24] InAs/AlSb, [25] InGaAs/InGaAsP, [26] and Ge 2 Te 3 /Sb 2 Te 3 , [27] to name a few. Most such inorganic-inorganic interfaces utilize isoelectronic substitution to retain the electrical conductivity and the high degree of crystallinity of the samples, which essentially grow epitaxially. An exception are the crystalline-amorphous interfaces as reported, e.g., in the Al 2 O 3 /TiO 2 [28] and Si [29] systems. With regard to high-quality interfaces, inorganic-organic superlattices offer an attractive option to reduce thermal conductivity compared to a homogeneous inorganic thin film. Owing to the large acoustic impedances between the inorganic and organic materials, we may anticipate considerably lowered thermal boundary conductance across the inorganic-organic interface. [30] Remarkable results have been reported for, e.g., TiS 2 with organic molecules intercalated either electrochemically [31] or chemically [32] from an organic solution. We have, on the other hand, fabricated ZnO/benzene [33,34] and TiO 2 /benzene [35,36] superlattices using the gas-phase atomic/molecular layer deposition (ALD/MLD) thin-film technique to demonstrate reductions in thermal conductivity of several orders of magnitude. Among the benefits of the ALD/MLD technique over solution-based intercalation routes is that it allows the precise control of the introduction frequency of the organic layers within the inorganic matrix.The uniting concept to lower the thermal conductivity of superlattice and nanolaminate structures is to suppress phonon Nanoscale superlattice structures are known to significantly suppress the thermal conductivity in thin films due to phonon scattering at the interfaces of the mutually different layers. Here it is demonstrated that in addition to the number of interfaces, their spacing within the film can lead to a reduction in thermal conductivity. The proof-of-concept data are for ZnO/benzene thin films fabricated through sequential gas-surface reactions in atomic/ molecular layer precision using the atomic/molecular layer deposition technique. In comparison to...

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Deposition of Organic- Inorganic Hybrid Materials by Atomic Layer Deposition

Cited by 81 publications

References 17 publications

Reversible and Irreversible Reactions of Trimethylaluminum with Common Organic Functional Groups as a Model for Molecular Layer Deposition and Vapor Phase Infiltration

Reversible and Irreversible Reactions of Trimethylaluminum with Common Organic Functional Groups as a Model for Molecular Layer Deposition and Vapor Phase Infiltration

Flexible Thermoelectric ZnO–Organic Superlattices on Cotton Textile Substrates by ALD/MLD

Thermal Conductivity Reduction at Inorganic–Organic Interfaces: From Regular Superlattices to Irregular Gradient Layer Sequences

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