The relationship of crystallinity between defects distribution with (100) ZnTe/GaAs using HWE growth was investigated by four crystal rocking curve (FCRC) and transmission electron microscopy (TEM). The thickness dependence of crystal quality in ZnTe epilayer was evaluated. The FWHM value shows a strong dependence on ZnTe epilayer thickness. For the films thinner than 6 ${mu}{ extrm}{m}$, the FWHM value decreases very steeply as the thickness increases. For the films thicker than 6 ${mu}{ extrm}{m}$, it becomes an almost constant value. At the thickness of 12 $mu extrm{m}$ with the smallest value of 66 arcsec. which is the best value so far reported on ZnTe epilayers was obtained. Investigation into the nature and behavior of dislocations with film thickness in (100) ZnTe/(100)GaAs heterostructures grown by Hot Wall Epitaxy (HWE). This film defects range from interface to 0.7 ${mu}{ extrm}{m}$ thickness was high density, due to the large lattice mismatch and thermal expansion coefficients. The thickness of 0.7~1.8 ${mu}{ extrm}{m}$ was exists low defect density. In the thicker range than 1.8 ${mu}{ extrm}{m}$ thickness was measured hardly defects.