Contribution à l’étude photoacoustique des endommagements surfaciques du monocristallin CuInSe2 implanté de xénon

Abstract

In this thesis are reported the results of a comparative study on the effects of implanted xenon ions at high energies (40 and 80 keV) with the dose of 51016 ions/cm2 on the electrical, morphological and near-infrared optical properties of CuInSe2 single crystals. This compound is used as the absorbing layer and is known for its resistance to radiation damages. The characterizing techniques that have been used were the four points probe, a scanning electron microscope (SEM) and a high-resolution photoacoustic spectrometer (PAS) of the gas-microphone type. The latter was used to measure the acoustic spectral response close to the fundamental edge of CuInSe2, of which the absorption coefficient spectral dependence of the implanted layer has been extracted from that of the bulk substrate using a newly developed software that takes into account the optical and thermal reflections within and at the samples’ interfaces. The experimental results have been correlated to those obtained by simulation using the SRIM software. Irradiation with xenon inflicted significant damage on the surface of CuInSe2 crystals leading even to the formation of a complex crater structure. Nevertheless, it is found that the implanted samples’ absorption coefficients have close to the absorption edge remained as high as those of the unimplanted ones. The whole process did not lead to amorphization. Chemical defects’ states resulting from vacancies of selenium were the mostly affected.