Structure variation of the index of refraction of GaAs-AlAs superlattices and multiple quantum wells

We present for the first time a detailed calculation of the index of refraction of various GaAs-AlAs superlattices. The calculation is performed by using a hybrid approach which combines the kp method with the pseudopotential technique. Appropriate quantization conditions account for the influence of the superstructures on the electronic properties of the systems. The results of our model are in very good agreement with the experimental data. In comparison with the index of refraction of the corresponding AlGaAs alloy, characterized by the same average mole fraction x̄ of Al, our results indicate that the superlattice index of refraction values attain maxima at the various quantized transition energies. For certain structures the difference can be as large as ∼2%. These results suggest that the waveguiding and dispersion relation properties of optoelectronic devices can be tailored to design for specific optical application by an appropriate choice of the superlattice structure parameters.