Hydrogen—Shallow-Level-Defect Complexes in Silicon

Hydrogen—Shallow-Level-Defect Complexes in Silicon 

The interaction of hydrogen with shallow donors and shallow acceptors in silicon is a problem of particular current interest and controversy. In the case of group V donors or group III acceptors, the donor or acceptor 

We proceed now to the detailed treatment of the theory of acceptor and donor systems, summarizing experiments as necessary to make contact with the theory and as appropriate to construct complete pictures of the defects. We collect and compare the results of many theoretical treatments, not all of which are in agreement. 

The most commonly accepted model for the hydrogen-acceptor pairs locates H at the BC site (see Fig. 4). This model was originally proposed for the H—B complex on the basis of satisfied bonds to explain the increased resistivity (Pankove et al., 1983), SIMS profiles (Johnson, 1985), and a hydrogen local-mode frequency consistent with a perturbed hydrogen-silicon bond (Pankove et al., 1985 Johnson, 1985 Du et al., 1985). The acceptor deactivation by atomic hydrogen was subsequently observed for Al, Ga, and In acceptors in silicon (Pankove et al., 1984). Hydrogen local-mode vibrations were identified as well for the H—Al and H—Ga complexes (Stavola et al., 1987). The boron vibrational frequency for the H—B pair was first identified by Stutzmann (1987) and Herrero and Stutzmann (1988a). 

Recent channeling studies have been interpreted to indicate H—B pairs with hydrogen distributed between both the BC and Si—AB sites, with a preference for the BC site at low temperatures. (Marwick et al., 1987, 1988 Bech Nielsen et al., 1988). The boron is estimated to be off the substitutional site by roughly 0.2-0.3 A. This is consistent with the PAC measurements of the similar H—In pair, where the Si—AB site is favored at higher temperatures (T 150 K), but the BC site is favored at lower temperatures (Wichert et al., 1987, 1988 Wichert, 1988). Also from the PAC studies, the H—In defect is found to anneal with a dissociation barrier estimated to be about 1.3 eV (Wichert et al., 1987). 

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V. Hydrogen—Shallow-Level-Defect Complexes in Silicon... 

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