FRACTAL STRUCTURE IN OPTICAL-SPECTRA OF FIBONACCI SUPERLATTICES

We present the results of theoretical and experimental studies of GaAs /GaAlAs Fibonacci superlattices. The normal-incidence reflectance was measured for a Fibonacci superlattice in the temperature range from 20 to 300 K. We develop a simple model to predict the reflectance theore tically. The energy levels are calculated with the help of the envelop e-function approximation and the Kohmoto-Kadanoff-Tang renormalization -group method. The model predictions are in good agreement with the ex periment. The electronic structure of Fibonacci superlattices exhibits multifractal properties, which manifest themselves also in the experi mental reflectance spectra.