MODULATED ELLIPSOMETRY FOR CHARACTERIZATION OF MULTIPLE-QUANTUM WELLS AND SUPERLATTICES

Recently the capability of photomodulated spectroscopic ellipsometry for complete non-destructive optical characterization of GaAs/AlGaAs multiple quantum well (MQW) samples was demonstrated. This technique is particularly well suited for identifying higher quantized transitions and determining sample parameters, such as well thickness, band offset and aluminium content. In this paper modulated ellipsometry is applied to MQW and superlattice samples in the AlGaAs/GaAs material system. The results are compared with calculations of the anisotropic dielectric function based on the solution of Schrodinger's equation for the confined state energies and wavefunctions. Franz-Keldysh-like features in the E0 region of the barrier material are included in the model. The results are compared with photoluminescence, photoreflectance, and conventional spectroscopic ellipsometry and sensitivity limits of modulated spectroscopic ellipsometry are given.