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Structural properties of AlN films deposited by plasma-enhanced atomic layer deposition at different growth temperatures



Crystalline aluminum nitride (AlN) films have been prepared by plasma-enhanced atomic layer deposition (PEALD) within the temperature range from 100 to 500 °C. A self-limiting, constant growth rate per cycle temperature window (100–200 °C) was established which is the major characteristic of an ALD process. At higher temperatures (>225 °C), deposition rate increased with temperature. Chemical composition, crystallinity, surface morphology, mass density, and spectral refractive index were studied for AlN films. X-ray photoelectron spectroscopy (XPS) analyses indicated that besides main Al[BOND]N bond, the films contained Al[BOND]O[BOND]N, Al[BOND]O complexes, and Al[BOND]Al metallic aluminum bonds as well. Crystalline hexagonal AlN films were obtained at remarkably low growth temperatures. The mass density increased from 2.65 to 2.96 g/cm3 and refractive index of the films increased from 1.88 to 2.08 at 533 nm for film growth temperatures of 100 and 500 °C, respectively.