Transmission electron microscopy (TEM) is used to study the microstructural properties of porous silicon layers (PS) and of the epitaxial Si layers grown on top of the PS.A more dense silicon layer exists in the upper part of the porous silicon.The defect density of the epitaxial layers is found to depend strongly on the morphology of the porous Si layers,and on the deposition temperature.A defect-free epi-Si layer with 800nm thickness can be obtained when depositing on a low porosity layer at 725 deg C.
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