Evaluation of thickness and strain of thin planar layers of InAs on GaAs(001) using spectroscopic ellipsometry

Abstract

We develop a technique for accurately measuring thickness of planar InAs films grown on (001) GaAs by spectroscopic ellipsometry, using bulk optical constants. We observe that the critical point structure for the E1 and E1 + Δ1 transitions extracted from the measured dielectric properties varies with strain in the layer. Transmission electron microscopy confirms the extracted thickness and measures the residual strain based on the dislocation spacing in the film. At small thickness, the E1 critical point is seen to markedly deviate from the dependence predicted by deformation potential theory and appears to be consistent with additional quantum confinement effects.