Thermal defects in silicon doped with rare-earth elements

The process of thermal defect generation in Si doped with rare-earth elements (REE) at temperatures of 450, 650, and 800 0C is investigated by using Hall effect and IR absorption methods. It is found that REE suppress the formation of thermal donors and electrically passive oxygen precipitates. It is shown that oxygen removal from the interstitials during the heat treatment (HT) at 650 and 800 0C in Si:REE is slowed down, but during the HT at 450 0C it is speeded up in comparison to a test (undoped) material. The experimental results obtained are accounted for by the interaction of oxygen with REE atoms, which leads to the formation of stable complexes at temperatures < 500 0C, and to the formation of metastable complexes of REE with O at higher temperatures. (author)