Molecular Hybrid Structures by Atomic Layer Deposition – Deposition of Alq₃, Znq₂ and Tiq₄ (q = 8‐hydroxyquinoline)

Abstract

Atomic layer deposition (ALD) is traditionally used for deposition of inorganic compounds, metals, organic polymers, and hybrid inorganic/organic materials. In all these materials, the structural framework is based on covalent or metallic bonds. The present paper demonstrates the growth of thin films of metal-organic films in which weak Van der Waals forces are important. Thin films of metal quinolines based on 8-hydroxyquinoline (q) and aluminum (Alq 3 ), zinc (Znq 2 ), and titanium (possibly Tiq 4 ) have been deposited using ALD in the temperature range 85-200 8C. The growth rates decrease with increasing temperature from 0.7-0.4 nm per cycle at 85 8C, to zero at 200 8C. The growth dynamics have been investigated using a quartz crystal microbalance (QCM). It is found that an excess of metal precursor will etch the films. The Alq 3 material is stable towards exposure to water during deposition. The photoluminescent properties of selected metal quinoline films are reported.

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

“…Aromatic 8-quinolinol has been used together with TMA, DEZ and TiCl 4 [ 13 , 35 ]. The deposition temperature ranged from 85 to 200 °C.…”

“…The growth rate gradually decreased with increasing temperature for all processes and no growth was observed in the films deposited at 200 °C. Significant photoluminescent activity was observed for the Al- and Zn-based hybrids whereas in the Ti-containing films a detectable but only small activity was perceived [ 35 ].…”

Titanium dioxide thin films by atomic layer deposition: a review

“…After this, attention regarding the organic precursors has shifted more and more on aliphatic and aromatic organic alcohols, amines and carboxylic acids [9]. In most of the works TiCl4 has been used as the Ti precursor; it has been combined with ethylene glycol [847,848], glycerol [847,849], 8-hydroxyquinoline [842,850], ethanolamine [811], malonyl chloride [811] and 4,4'-oxydianiline [851,852]. Ideally, the growth of a hybrid thin film takes place via self-saturating ligand-exchange reactions between e.g.…”

Hybrid nanomaterials through molecular and atomic layer deposition: Top down, bottom up, and in-between approaches to new materials

“…Similar to Alucone but not necessarily a large enough group to warrant their own section are hybrid materials grown with metal quinolines such as Alq 3 , Znq 2 , and Tiq 4 where q=8-hydroquinoline 77,78 . When TMA is paired with one of the quinolines the GPC was shown to be fairly high varying from 0.4 nm -0.7 nm, decreasing with temperature.…”