ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Al2O3 grown by Atomic Layer Chemical Vapour Deposition (ALCVD) on n-type 4H-SiCwith a nominal thickness of 100nm has been characterized by Grazing Incidence X-Ray Diffraction(GIXD) and Specular X-Ray Reflectivity (SXR) measurements. After post-deposition, the sampleswere annealed at different temperatures and durations in argon atmosphere. The GIXD results revealcrystallization at temperatures above 900°C, most likely in the form of θ-Al2O3 or γ-Al2O3.However, the formation of a new, non-stoichiometric Al2O3 phase cannot be excluded. Thecrystalline domain size, evaluated from the peak FWHMs after subtraction of the instrumentalbroadening, is found to be almost equal (18±1nm), independent of T in the range 900°C≤T≤1100°Cand time in the range 1h≤t≤3h. From SXR, mass density profiles are derived. Whereas the as grownfilm exhibits the lowest mass density, at 800°C a low-density interface layer forms. At the sametime, it appears that the initial crystallization starts at the surface. At 900°C, the density increasessharply (this process involves film crystallization) and the film thickness correspondingly reduces.Whereas the density increase and thickness reduction still continue for T〉900°C (tendency to thedensity α-Al2O3), the density of the interfacial layer has a minimum at 900°C and graduallyincreases for higher temperatures. From Atomic Force Microscopy (AFM) investigations it could berevealed that the starting of the crystallization at 900°C is accompanied with a substantial surfaceroughening. For annealing at higher temperatures, the surface roughness is in the range of the one ofthe as-grown sample (about 6Å)
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/17/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.556-557.683.pdf
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