Formation of dislocation loops in silicon by ion irradiation for silicon light emitting diodes

Abstract

We have studied the influence of the ion species, ion energy, fluence, irradiation temperature and post-implantation annealing on the formation of shallow dislocation loops in silicon, for fabrication of silicon light emitting diodes. The substrates used were (100) Si, implanted with 20-80 keV boron at room temperature and 75-175 keV silicon at 100 and 200 degrees C. The implanted fluences were from 5 x 10(14) to 1 x 10(15) ions/cm(2). After irradiation the samples were processed for 15 s to 20 min at 950 degrees C by rapid thermal annealing. Structural analysis of the samples was done by transmission electron microscopy and Rutherford backscattering spectrometry. In all irradiations the silicon substrates were not amorphized, and that resulted in the formation of extrinsic perfect and faulted dislocation loops with Burgers vectors a/2 LT 110 GT and a/3 LT 111 GT , respectively, sitting in {111} habit planes. It was demonstrated that by varying the ion implantation parameters and post-irradiation annealing, it is possible to form various shapes, concentration and distribution of dislocation loops in silicon. (C) 2008 Elsevier B.V. All rights reserved.