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Correlation between optical properties of MBE films of AlN and morphology of their surface

In this work we revealed correlation between presence of surface defects and peculiarities in ellipsometric spectra and hence in optical properties of AlN films grown by ammonia MBE technique. We propose to use this fact for the fast and non‐destructive checking of film quality. Principal criterions of AlN films quality was both magnitude of phase deviation in maximum and/or a value of false (effective) absorption in transparency field of AlN calculated in according with our model. Our experiments were based on using of spectroscopic ellipsometry (SE). Atomic force microscopy (AFM) was used for determination of geometric size of overlayer roughness. Quantitative parameter related with surface morphology γs was proposed and influence of surface defects upon phase of light reflected was studied to evaluate surface quality from ellipsometric spectra at once, i.e. without any model calculations. Besides, an impact of surface defects upon film extinction coefficient is demonstrated in case when roughness is not taken into account. This approach could be useful for sorting identical films produced in routine growth procedure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)