Proximity getterihg by MeV-implantation of carbon: microstructure and carrier lifetime measurements

Abstract

The gettering efficiency of silicon implanted with carbon at a dose of 1 × 10 16 cm −2 and energies in the range of 0.33–10 MeV was tested by carrier lifetime measurements. After an intentional contamination of the sample back side with gold as a lifetime killer, on the front side we found values for the generation lifetime of the minority carriers in the range of 27–78 μs and 144–569 μs for the 2.4 MeV and 10 MeV implantation, respectively. These values are higher by 1–2 orders of magnitude as compared to unimplanted silicon. Furthermore, an anomalous doping effect of carbon was found which depends on the annealing method (furnace, RTA). The microstructure of the carbon-implanted layer was investigated by electron microscopy of cross-sectional samples showing dislocation loops which surround the stacking faults. These defects are located within a band of very small precipitates.