The interaction of hydrogen with deep level defects in silicon

Monatomic hydrogen is a very aggressive chemical specie, readily attacking Si-Si bonds, creating an unusual bond centred defect. It reacts especially with strained bonds in vacancies and those surrounding transition metal impurities. From these considerations, it is clear that hydrogen has a great effect on centres with deep levels, as these often involve unsaturated Si atoms or possess weak bonds. However, hydrogen can also react with itself and forms several passive defects, for example hydrogen molecules, H2 defects, platelets etc. In these quiescent forms, hydrogen lies in a reservoir, but it can be extracted during processing, by heat or radiation treatments and resume its aggressive behaviour.