Metalcones: Hybrid Organic–Inorganic Films Fabricated Using Atomic and Molecular Layer Deposition Techniques

Abstract

Hybrid organic-inorganic films can be deposited using atomic layer deposition (ALD) and molecular layer deposition (MLD) techniques. A special set of hybrid organic-inorganic films based on metal precursors and various organic alcohols yields metal alkoxide films that can be described as "metalcones." Many metalcone films are possible such as the "alucones" and "zincones" based on the reaction of trimethylaluminum and diethylzinc, respectively, with various organic alcohols such as ethylene glycol (EG). This paper reviews the previous work on metalcone MLD and discusses a variety of new metalcone systems. "Titanicones" are grown using TiCl4 and glycerol or EG and "zircones" are grown using zirconium tetra-tert-butoxide and EG. In addition, the organic alcohol can also be varied to change the properties within one metalcone family. For example, the glycerol triol precursor allows for more cross-linking and higher toughness in alucones than the EG diol precursor. Alloys can also be formed by combining metalcone MLD and metal oxide ALD. By varying the relative number of cycles of MLD and ALD, the composition and properties of the hybrid organic-inorganic films can be tuned from pure metalcone MLD to pure metal oxide ALD.

History of atomic layer deposition and its relationship with the American Vacuum Society

“…36 Combining ALD and MLD can also produce organic-inorganic alloys or nanolaminates, where the properties are tunable between pure inorganic and organic-inorganic. 37,38 The number of materials is nearly endless considering the metals and types of organic linkages available.…”

Organic and inorganic–organic thin film structures by molecular layer deposition: A review

“…When metal precursors are combined with alcohols or phenols, the resultant material is often called “metalcone” [27]. Most of the research has been focused on the aluminum-based alucones [12–13 15–16 38–39 81–97], but also zincones [13,33,38–39 46,51–52 56,94–95 98–103], titanicones [53,55,95,104–105], and zircones [54,87] have been studied.…”

“…Although the introduction of the MLD method dates back two decades, the number of articles featuring purely organic thin films is still quite limited. Nevertheless some reviews concerning MLD-based thin films have been published in the past: George et al [24] discuss the surface chemistry of MLD grown materials, addressing the problems which arise when using organic precursors in the growth process; Leskelä et al [25] shortly review the novel materials fabricated by ALD and MLD; George [26], George et al [27] and Lee et al [28] focus on metal alkoxide thin films; Yoshimura et al [29] discuss a possibility to utilize MLD in cancer therapy applications; King et al [30] describe fine particle functionalization by ALD and MLD; and the review by Zhou et al [31] covers all the organic interfaces fabricated by MLD.…”

Progress and future directions for atomic layer deposition and ALD-based chemistry

“…The various metal alkoxides defi ned by reacting organometallics and organic alcohols can be known collectively as "metalcones." 26 Additional classes of hybrid organic-inorganic fi lms can be defi ned using other organic precursors such as carboxylic acids. 27 The possibilities are nearly endless given the various organometallic precursors and large number of organic precursors.…”