Transmission electron microscopy studies of defects in HgCdTe device structures grown by molecular beam epitaxy

Transmission electron microscopy (TEM) was used to evaluate the microstruct ure of molecular beam epitaxy (MBE) grown (211)B oriented HgCdTe films. TEM analysis of in-situ doped p-on-n and n-p-n device structures will be prese nted. Under fully optimized growth conditions the substrate-epilayer interf ace is free of threading dislocations and twins, and a high degree of struc tural integrity is retained throughout the entire device structure. However , under non-optimal growth conditions that employ high Hg/Te flux ratios, t wins can be generated in the p-type layer of p-on-n device structure, resul ting in roughness and facetting of the film surface. We propose a mechanism for twin formation that is associated with surface facetting. TEM evaluati on of voids, threading dislocations and Te-precipitates in HgCdTe films are also discussed.