Estudos por espectroscopia Raman da heteroestrutura semicondutora InxGa1-xP/GaAs

Abstract

In this work, the technique Raman spectroscopy is used in order to study InxGa1-xP films grown with different thickness on GaAs (001). Two sets of samples grown by CBE (Chemical Beam Epitaxy) were analized: the first a GaAs buffer layer of 3000 Ǻ and the second with an 1800 Ǻ buffer layer. Concerning vibrational modes, it was possibleto conclude that for In concentrations around 50 % this alloy has a two mode behaviour. Polarized Raman spectra allowed to estimate the ordering degree of the samples. It was possible to observe strong disorder for all of then, with 0,l26 ≤ η ≤ 0,443. Photoluminescence measurements confirmed the disordering. The stress, the lattice parameters and the concentrationsin the alloys were obtained from the variations of the vibrational modes. The interdifusion of P atoms through the GaAs buffer layer previously observed by X-Ray measurements was confirmed. Finally, a comparative study showed that a sensible difference occur between the vibrational modes of the alloys belonging to each set (with different buffer layer thicknesses). Besides, the absorption coefficients, was also shown to be different for each set.