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 ars enide to form trimethylarsine and, dimethylarsine. An analogous reacti on 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 th e nucleation sites far hillocks. Analogous reactions have been observe d between the precursors and a range of other substrates which can in turn be used to explain the origin of hillocks in epitaxial layers gro wn onto these materials.