Hydrogen—Shallow-Level-Defect Complexes in Compound Semiconductors

Hydrogen—Shallow-Level-Defect Complexes in Compound Semiconductors 

In comparison with theoretical studies of the complexes in silicon, very little work has been done in the compound semiconductors. We now summarize the theoretical treatments reported by Briddon and Jones (1989) using local-density cluster methods. 

In the calculations of Briddon and Jones (1988), the BC site was found to be the stable site of hydrogen for the H—Be (H-acceptor) pair. The H—As and H—Ga separations were found to be 1.54 A and 1.77 A, respectively. The Aj frequency was computed to be 2083 cm-1, very close to the experimentally determined value of 2037 cm-1. An E-mode was also calculated to have a frequency of (383, 346) cm-1. (This pair of computed results should be degenerate differences are artifacts of method approximations.) 

The H—Si (H-donor) complex was also examined and the total-energy results were found to support the Si—AB configuration (this would be the analog of the P—AB position for a H—P pair in silicon). The Si—H distance was found to be 1.61 A and the As—Si distance was 2.73 A. The calculated hydrogen A, and E frequencies are 1592 cm-1 and (1046, 916) cm-1, respectively. The experimental values are 1717 cm-1 and 896 cm-1, respectively. 

In summary, the H-acceptor pairs appear to be very similar to their silicon counterparts, which we have discussed in depth. The H-donor pairs are similar in that the H occupies a silicon-antibonding site however, this is an antibonding site to the defect and not to the host as is found in silicon. It is also interesting to note that the computed hydrogen frequencies appropriate to the latter pairs are better described by theory than the silicon counterparts discussed earlier. It is not clear whether this is a consequence of the electronic-structure method used here, a natural consequence of the differences between the silicon and compound-semiconductor hosts, or simply an accident. 

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VI. Hydrogen—Shallow-Level-Defect Complexes in Compound Semiconductors... 

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