Deposition of AlQ3 Thin Films with Detectable Crystallinity without Post-Processing

Thin films of aluminum tris-(8-hydroxyquinolinate), AlQ3, are obtained by thermal evaporation at a residual pressure of ∼10–4 Pa on substrates with different temperatures. With a temperature difference of 40 degrees between the source and the substrate, a polycrystalline film is formed on it without post-growth annealing or treatment in solvent vapors. At a substrate temperature of 100°C, in the AlQ3 film on a continuous sublayer, dendritic objects of several micrometers in size are formed. At lower deposition temperatures (from 25 to –20°C), the films are amorphous and have usual fine-grained structure. Crystallization affects the electrical and physical properties of AlQ3 films. The development of this technique will make it possible to obtain functional structures (multilayer, hybrid, etc.) with a crystalline AlQ3 layer in a standard vacuum process.