Configurations and properties of hydrogen in crystalline semiconductors

We review the experimentally determined stable configurations of hydrogen in single-crystal semiconductors and compare these with theoretical predictions made by a variety of calculational methods. In undoped Si, hydrogen appears to occupy a near-bond-centered (BC) site between neighboring Si atoms, with a secondary local minimum in energy occurring at a tetrahedral interstitial (T) site. In B doped, p-type Si, hydrogen at the near-B site accounts for acceptor passivation. By contrast, in n-type Si, hydrogen at the anti-bonding (AB) position appears to be responsible for donor passivation. Recent results on the temperature and uniaxial stress-induced changes in the infra-red absorption spectra of hydrogenated acceptors and donors in Si, and their possible implications for the microstructures of these centers, are discussed. A correlation between the stable positions of hydrogen and normal (Mu) and anomalous (Mu*) muonium in Si is noted - Mu appears to occupy a T-site, and Mu* a BC-site. The evidence for the existence of several charge states of hydrogen in semiconductors is reviewed, along with the implications for diffusion of these species in the lattice. Unintentional incorporation of hydrogen during wafer polishing and etching in acids is also examined. (author) 83 refs., 10 figs., 1 tab