A STUDY OF VOID DEFECTS IN METALORGANIC MOLECULAR-BEAM EPITAXY-GROWN HGCDTE

Void defects that occur under Hg deficient conditions during the metal organic molecular beam epitaxy (MOMBE) growth of HgCdTe have been char acterized using secondary electron microscopy (SEM) and energy dispers ion spectrometry (EDS) mapping as well as by EDS quantitative analysis . For a set of HgCdTe samples grown under a range of Kg fluxes, it was found that the surface morphology had a significant dependence on the Hg flux. An optimum growth window defined by a narrow range of Hg flu xes was identified in which there exists a smooth surface with few voi ds, whereas at either side of the Hg window surfaces were rough. This surface morphology correlated very well with a minimum in the x-ray li ne widths and maximum hole concentration and mobility values. This cor relation is important for the growth of HgCdTe materials and subsequen t device fabrication. Several types of void morphologies have been obs erved with different correlation to Te and Hg. It was found that there is a pronounced Te enrichment and Hg deficiency associated with most of the developed voids, as compared to the composition of the HgCdTe f ilms. It was also found that most of the voids originated within the H gCdTe film. A mechanism for void formation and growth is proposed. In addition, it was found that annealing caused the voids to separate fro m the HgCdTe film.