The microstructures of vacancy-type defect in HgCdTe (MCT) samples grownunder micro-gravity condition were studied by positron lifetime measurements. Theresults showed that
the defect concentrations in the samples grown under spacendcro-gravity were lower than those grown under earth gravity on the ground. Thedistribution of defect concentration along the axial in the samples grown under spacemicro-gravity were more uniform than that grown under earth gravity on theground.