MODULATED ELLIPSOMETRY FOR CHARACTERIZATION OF MULTIPLE-QUANTUM WELLSAND SUPERLATTICES

Recently the capability of photomodulated spectroscopic ellipsometry f or complete non-destructive optical characterization of GaAs/AlGaAs mu ltiple 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 applie d to MQW and superlattice samples in the AlGaAs/GaAs material system. The results are compared with calculations of the anisotropic dielectr ic function based on the solution of Schrodinger's equation for the co nfined state energies and wavefunctions. Franz-Keldysh-like features i n the E0 region of the barrier material are included in the model. The results are compared with photoluminescence, photoreflectance, and co nventional spectroscopic ellipsometry and sensitivity limits of modula ted spectroscopic ellipsometry are given.