X-ray diffraction phenomena in elastically distorted crystals

Characterization of defects in mono-like silicon for photovoltaic applications using X-ray Bragg diffraction imaging

Rocking curve imaging (projection and section X-ray topography) has been used to study the generation and propagation of defects at the junctions between and above the seed crystals in mono-like silicon ingots. The images of different kinds of defects such as precipitates, dislocations and twins in the integrated intensity, full width at half-maximum and peak position maps resulting from the experiment have been studied. The qualitative and quantitative information that can be extracted from these maps, in particular the contrast of the images of the various defects, is discussed. These defects have a detrimental effect on solar cell efficiency and their detailed investigation allows clues to be obtained in order to improve the growth process. This work shows that synchrotron X-ray diffraction imaging techniques, because of their high angular resolution (<10-4°) and large field of view (several mm2), constitute a powerful tool for investigating the initial stages of growth of directionally solidified mono-like silicon.

Contrast in transmission X-ray diffraction topographs of growth defects in the core of SrLaGaO4single crystals

Defects in the core of SrLaGaO4single crystals, grown by the Czochralski method using a [001]-oriented seed, were studied by transmission X-ray diffraction projection topography. Topographs were taken with radiation from a laboratory source and with high-energy radiation available at the ESRF beamline ID19 in Grenoble. The contrast of the investigated defect images was analysed for various diffraction vectorsgand for various values of the product μ0t(μ0is the linear absorption coefficient andtthe crystal thickness). This allowed the contrast formation to be studied as a function of absorption. The results of the analysis confirm the model of crystal lattice deformation around rod-like volume defects in SrLaGaO4crystals.