A study of the structure and electrical properties of CdxHg1−xTe grown by metalorganic vapor phase epitaxy (interdiffused multilayer process)

Abstract

Epitaxial layers of CdxHg1−xTe (CMT) have been grown by the interdiffused multilayer process (IMP) at 350 °C. The electrical properties are fixed by the equilibrium conditions of the interdiffused structure and subsequent cooling of the layer in a Hg ambient. Indiffusion of Hg during cooldown can be prevented by the growth of a 1000-Å-thick cap layer of CdTe. X-ray double-crystal rocking curves for the 400 reflections have been measured to find whether IMP introduces any residual structure or strain into the CMT. For CMT grown onto CdTe/GaAs, a postgrowth anneal of 30 min or longer reduces rocking curve widths to below 100 arc s, with a best value of 55 arc s. The best value on CdTe substrates was 72 arc s. Depth profiling of x-ray peak widths for CMT/CdTe/GaAs structures has shown that the CMT/CdTe interface improves the crystalline quality of the epilayer. One contribution to peak width broadening has been identified as pyramidlike morphological defects. Epitaxial layers have been grown onto GaAs substrates with regions >1 cm2 free of pyramids.