Thermal Donor Removal by Rapid Thermal Annealing: Infrared Absorption

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Abstract
Rapid thermal annealing of thermal donors in Si with 10 sec anneal times at temperatures between 600 and 1000 °C has been investigated by infrared absorption at 80 K. Thermal donors A through D, which are identified by excited state absorption, are present in as-grown Czochralski Si; whereas excited states for donors A through F as well as photoionization of thermal donors are observed after extended heating at 450 °C. The temperature required for rapid thermal annealing is lower when only donors A through D are present. Removal of thermal donors A through F by rapid thermal annealing at temperatures > 800°C restores 7 to 8 oxygen atoms to interstitial sites per electricallӯ measured donor removed. This ratio supports oxygen cluster models for thermal donors but does not support previous suggestions that such clusters are embryonic forms of high temperature oxygen precipitates.