Dislocation reduction in HgCdTe on GaAs by thermal annealing

Abstract

The effect of dislocation reduction in HgCdTe epilayers grown on GaAs substrates by molecular-beam epitaxy has been studied by thermal annealing in a Hg atmosphere. It is found that dislocation movement in the HgCdTe epilayer is activated when the annealing temperature is higher than 250 °C. This behavior is analyzed by a simple model that was applied to dislocation reduction in GaAs layers on Si. The model is based on the dislocation movement under thermal stress. Thermal cycle annealing was also carried out. From the experiments and the model analysis, it is suggested that a relation between the dislocation reduction and total annealing time is almost independent of the annealing temperature. Furthermore, the activation energy of dislocation movement in the HgCdTe epilayer is estimated to be about 1 eV, which is almost the same value as Hg vacancy formation energy. It is, therefore, likely that dislocations in the HgCdTe epilayer interact with Hg vacancies, so that the dislocation annihilation and reemission take place.