Observation of new critical point in InxAl1−xAs alloy using spectroscopic ellipsometry

Using a spectroscopic ellipsometry, pseudodielectric functions 〈ɛ〉 of InxAl1−xAs ternary alloy films (x = 0.43, 0.62, 0.75, and 1.00) from 0.74 to 6.48 eV were determined. Fast in-situ chemical etching to effectively remove surface overlayers using charge-coupled device detector and to avoid the reoxidation of the surface of films prior to the ellipsometric spectrum measurement was performed. At the high energy region, an additional critical point structure which is interpreted as the E′1 transition from the band structure calculation of the linear augmented Slater-type orbital method was reported.