Tritertiarybutylaluminum as an organometallic source for epitaxial growth of AlGaSb

Abstract

A new organometallic source, tritertiarybutylaluminum (TTBAl), has been used in growth of AlxGa1−xSb epilayers by low pressure organometallic vapor phase epitaxy. Ternary alloys were grown over the whole composition range 0<x≤1 on GaSb and GaAs substrates from TTBAl, triethylgallium, and triethylantimony (TESb) or trimethylantimony (TMSb). All layers exhibited mirror surface morphologies. Photoluminescence was observed for layers with x<0.2, the composition that corresponds to the indirect transition. The background of C and O in AlSb grown with TESb was ∼2×1018 and ∼6×1019 cm−3, respectively, and ∼1.5×1019 and ∼1.5×1019 cm−3, respectively, for AlSb grown with TMSb. All layers exhibited p-type conductivity with hole concentration increasing with x, and saturating ∼5×1018 cm−3 for x=1, which is about 10 times lower compared to layers grown with conventional Al sources.