Damage evolution and amorphization in semiconductors under ion irradiation

The interaction of energetic ions with crystalline semiconductors may cause defect formation and amorphization both by nuclear and electronic energy deposition which occur simultaneously with different strength. In the energy range of dominating nuclear energy loss the transition to the amorphous state depends on the energy received by the target atoms through nuclear interactions, i.e. on ion mass and energy, and on the irradiation temperature which can favour dynamic defect annealing. Regarding the damage evolution, different groups of semiconductors are observed. In many materials (e.g. elemental and binary III-V semiconductors, SiC) a continuous increase of the damage concentration up to amorphization is found below characteristic critical irradiation temperatures. In some other materials (AlAs, GaN) the damage concentration increases stepwise until amorphorphization occurs, and in few other cases (ZnO, CdTe) amorphization is prevented even at 15 K. In case of swift heavy ion (SHI) irradiation with dominating electronic energy loss, heavily damaged tracks are formed above critical values of the energy deposition in some materials (e.g. InP, InAs, InSb, GaSb), which may agglomerate to continuous amorphous layers. In other semiconductors (e.g. Si, Ge, GaP, GaAs, AlAs) so far no track formation but only the formation of point defects and point defect complexes was observed. In the present contribution the state of the art of damage evolution and amorphization occurring at temperatures equal to and below room temperature in covalent and ionic-covalent semiconductors is summarized and possible mechanisms are discussed to understand the experimental results. (C) 2011 Elsevier B.V. All rights reserved.