Obliquely deposited tris(8-hydroxyquinoline) aluminium (Alq3) biaxial thin films with negative in-plane birefringence

Autor:	M J Brett, B. Szeto, P C P Hrudey, J Gospodyn, J C Sit
Rok vydání:	2007
Předmět:	Materials science Birefringence Scanning electron microscope business.industry chemistry.chemical_element Substrate (electronics) Atomic and Molecular Physics and Optics Optics Tilt (optics) chemistry Effective medium approximations Aluminium Thin film business Deposition (law)
Zdroj:	Journal of Optics A: Pure and Applied Optics. 9:457-462
ISSN:	1741-3567 1464-4258
DOI:	10.1088/1464-4258/9/5/006
Popis:	Tilted columnar biaxial thin films were fabricated by thermally evaporating tris(8-hydroxyquinoline) aluminium (Alq3) at oblique angles of incidence α≥65° measured from the substrate normal. Variable angle spectroscopic ellipsometry and Bruggeman effective medium approximations were used to characterize the structure and the optical anisotropy of the films. The structural characteristics were also examined using scanning electron microscopy, revealing a lack of column broadening and a predominantly circular column cross-section. The films also exhibited larger column tilt angles than those typical of inorganic tilted columnar films. These structural properties gave rise to optical anisotropy leading to negative values of in-plane birefringence of the films that increased in magnitude with deposition angle. The observed negative in-plane birefringence contrasts with the typical behaviour of inorganic biaxial columnar thin films which exhibit positive values of in-plane birefringence, with peak values obtained for films grown at angles of 60°
Databáze:	OpenAIRE
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