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

Abstract

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°C, but is observed both in the n- and p-type above 200°C. 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°C is very different from that below 250°C. The result suggests that platelets are formed from hydrogen-complexes other than the H 2 * above 250°C.