Fermi-level dependence of formation of hydrogen molecules in crystalline silicon

摘要

We report a systematic investigation on the Fermi-level dependence of the formation of two different types of hydrogen molecules in silicon. Hydrogen molecule at the tetrahedral (T) site (H_2(T)) is formed only in heavily doped n-type below 200℃, but is observed both in the n- and p-type above 200℃. The temperature dependence is due to the increase of the thermally activated carrier concentration. The possible precursors of the H_2(T) are H~+ (BC) and H~0(BC) in the p-type, and H~-(T) and H~0 in the n-type. The Fermi level dependence of the formation of the hydrogen molecule trapped in platelets (H_2(p)) above 250℃ is very different from that below 250℃. The result suggests that platelets are formed from hydrogen-complexes other than the H_2~* above 250℃.