FORMATION OF ELECTRICALLY ACTIVE-CENTERS BEYOND THE STOPPING RANGES OF IONS IMPLANTED IN HEATED SILICON

Deep-level transient spectroscopy was used to study ion-implantation-i nduced defects in silicon beyond the stopping range of the ions. After ion implantation at a target temperature T-i less than or equal to 70 0 degrees C, discrete levels were observed in silicon, whose filling t ime depended logarithmically on the charging pulse duration. For impla ntation at T-i greater than or equal to 800 degrees C bands of several levels were identified in the spectrum. These levels were characteriz ed by fast (t<10 mu s) simultaneous filling and their concentration wa s proportional to the square loot of the ion dose. No level formation was observed at a target temperature T-i=1000 degrees C. It is suggest ed that at T-i less than or equal to 700 degrees C closely spaced poin t centers (as within rodlike defects) are responsible for the formatio n of these levels, whose filling is impeded by Coulomb repulsion. At t arget temperatures between 800 and 100 degrees C the defects formed ar e distributed at the edges of the dislocation loops. (C) 1996 American Institute of Physics.