In a lengthy review, it was recalled that H was a common impurity which was either deliberately introduced, or penetrated into the crystal during processing. It then interacted with broken or weak covalent bonds such as those found at extended and localized defect centers. The main results of these covalent interactions were shifts of energy levels out of, or into, the gap and new optical activity such as infra-red absorption and Raman scattering. The shifts in energy level led to passivation or activation of the electrical activity of various centers. The H could also interact with the perfect crystal and with itself, sometimes leading to the formation of extended defects such as platelets. The H could also act as a catalyst, and markedly enhance the diffusivity of interstitial O in Si. It was noted that the thermal stability of complexes which contained H ranged, from room temperature, up to several hundreds of C. The diffusion of H was trap-limited up to relatively high temperatures. The H normally existed in more than one configuration and charge state in semiconductors.

S.K.Estreicher: Materials Science and Engineering R, 1995, 14[7-8], 319-412