The origin of hillocks in (Hg,Cd)Te grown by MOVPE

Dimethylcadmium, a precursor for the metalorganic vapor phase epitaxy of mercury cadmium telluride, has been shown to react with gallium arsenide to form trimethylarsine and, dimethylarsine. An analogous reaction occurs between di-iso-propyltelluride and gallium arsenide to form iso-propylarsine and di-iso-propylarsine. It is proposed that if these reactions remove sufficient arsenic from a gallium arsenide substrate, metallic droplets will form on the wafer surface thereby creating the nucleation sites far hillocks. Analogous reactions have been observed between the precursors and a range of other substrates which can in turn be used to explain the origin of hillocks in epitaxial layers grown onto these materials.