Charge Carrier Lifetime Modification in Silicon by High Energy H+ or He+ Ion

H⁺ or He⁺ was implanted at energies of 1, 2.5 and 4 MeV into n-type 〈100〉 4–7.5 Ω cm CZ-Si with doses in the range from 3 × 10¹⁰/cm² to 1 × 10¹²/cm². A reduction in minority carrier lifetime was measured by the microwave photoconductive decay (μ-PCD) method using a 904 nm laser pulse. It was shown that the modified lifetime can be directly measured by μ-PCD when the damaged region and the excess charge pocket generated by the laser pulse exactly overlap. This was the case for 4 MeV H⁺ implantation. For shallower defects, the measured lifetime value is influenced by the diffusion process of excess minority carriers. To extract the real lifetime in this case, a three layer model is presented.

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