Electrically active defects in deep preamorphized single-crystal silicon layers

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Abstract
High-energy Si and Ge implantations have been used to form thick (∼1 μm) amorphous films which permit direct electrical characterization of the layers after solid phase regrowth. The dislocation loops observed at the original amorphous–crystalline boundary after regrowth are fundamental to the preamorphization process and three dominant deep levels at Ec−0.40 eV, Ev + 0.47 eV, and Ev + 0.26 eV have been found to be spatially localized in the same region as the dislocation loops. The level at Ev+0.47 eV is most likely to be responsible for the spatially localized generation current also arising from the same region. The level at Ev+0.26 eV and a level, which was less dominant in the deep level transient spectroscopy measurements, at Ec−0.19 eV show features consistent with a defect displaying charge state controlled metastability. The density of these levels implied a high degree of reconstruction around the perimeter of the loops. The effects due to nitrogen decoration of the dislocations have also been investigated. The deep levels found within the regrown layers are believed to be associated with other dislocations which have not typically been seen in shallower preamorphized layers.