Selective and non-selective wet-chemical etchants for GaSb-based materials

A series of wet-chemical etchants for materials lattice-matched to GaSb was investigated. The etch rates for GaSb, AlAsSb, InAsSb and InAs with etch solutions based on KNa-tartaric acid (C₄H₄KNaO ₆), citric acid (C₆H₈O₇) and hydrochloric acid were determined and the selectivities for the four different etching solutions are shown. The applicability of the selectivity between GaSb and InAs (respectively InAsSb) with C₄H₄KNaO ₆:HCl: H₂O₂:H₂O (selectivity higher than 15:1) and C₆H₈O₇H₂O₂ (selectivity around 1:100) is proved by a substrate removal experiment. Also a new etchant for AlAsSb is proposed: HCl:H₂O₂:H ₂O₂ etches AlAsSb versus GaSb with a selectivity of 5:1 and the GaSb surface underneath is smooth and without any remaining particles of oxidized aluminium.