The Shockley-Read-Hall (SRH) lifetime is a very important parameter in silicon bipolar power devices that determine switching characteristics.
As for carrier lifetime control, recombination center levels in impurities-doped silicon are dependent on the properties of impurities and silicon materials, but not on the amount of impurities.
Preceding researchers studied diffusion of impurities and radiation action for recombination center levels by means of Au, Pt, electron irradiation, proton irradiation, etc.
Yu Nam Chol, a researcher at the Science Engineering Institute, has determined new recombination center levels in n-type silicon with gold and platinum, and investigated the effectiveness of the levels for low-level and high-level injection lifetime control.
At injection levels below 3×1013cm-3, reverse recovery technique was used, while open-circuit carrier decay (OCCD) technique was employed at levels above 1015cm-3. He performed lifetime measurements in the temperature interval of 303~403K. He studied the deep levels introduced by diffusion using DLTS, and calculated the corresponding SRH lifetime, and finally compared it with the measured values. The comparison suggests that low-level lifetime is mainly controlled by defect B located at 0.54eV below the conduction band, and high-level lifetime by defect A located at 0.25 eV.
The result shows that the recombination center levels estimated from DLTS measurement are dominant levels in n-type silicon doped gold and platinum.
If further information is needed, please refer to his paper “Analysis of recombination center levels in gold and platinum doped n-type silicon” in “Journal of Power electronics and devices”.
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