Effect of incident angle in spectral ellipsometry on composition control during molecular beam epitaxial growth of HgCdTe

The effect of incident angle in spectral ellipsometry (SE) on composition control of Hg1-xCdxTe grown by molecular beam epitaxy (MBE) was investigated. Although a small uncertainty in the incident angle tends to have a significant impact on the ellipsometric data, and therefore the composition data, it was found that the incident angle uncertainty could be corrected in the SE model calculation, resulting in an "optimized" incident angle that would give the best fit between measured and calculated ellipsometric data. Experimental data supporting this simple corrective or optimization procedure for the incident angle are presented.