Effect of hydrogenation on the properties of extended defects in semiconductors

Hydrogen is introduced in semiconductors in order to improve their electronic properties. It can also be present in many cases as a result of material preparation. We first briefly review the various means and mechanisms of introduction of hydrogen, and its influence on the shallow levels. Assessment of the electrical properties of extended defects is reviewed, with a special emphasis on the beam injection techniques. It is shown how hydrogenation can passivate the electrical activity of deep levels associated to grain boundaries, dislocations, surfaces or interfaces, in crystalline semiconductors. The issues of the thermal stability of the hydrogen in the samples as well as that of the prevention against surface damage during hydrogen treatments are discussed.