MULTIPLE-ANGLE-OF-INCIDENCE ELLIPSOMETRY FOR GAAS GAPAS SUPERLATTICES/

In this paper we present results of multiple-angle-of-incidence (MAI) ellipsometry for strained GaAs/GaPxAs1-x superlattices (SL) with the c omposition x approximate to 0.4 and with different layer thickness in the range of 8-80 nm. SLs have been grown on the GaAs (100) substrates by chemical vapour deposition. The geometrical parameters of SLs have been determined by X-ray diffraction patterns. From MAI measurements the thickness and optical constants of SL films have been calculated b y solving inverse ellipsometric problem. The latter was solved by usin g Tichonov's regularization algorithm. The anisotropic film model of S L and capping isotropic layer were taken into account at solving. The optical constants obtained together with the full thickness of SL have been related to the SL microstructure using an effective medium appro ximation. These results are compared with ones obtained by far-infrare d reflection spectroscopy in the ''reststrahlen'' band region. The qua lity of SLs in connection with technology of thin films growth are dis cussed. (C) 1998 Elsevier Science Ltd. All rights reserved.