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 (C 4 H 4 KNaO 6 ), citric acid (C 6 H 8 O 7 ) 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 C 4 H 4 KNaO 6 :HCl: H 2 O 2 :H 2 O (selectivity higher than 15:1) and C 6 H 8 O 7 :H 2 O 2 (selectivity around 1:100) is proved by a substrate removal experiment. Also a new etchant for AlAsSb is proposed: HCl:H 2 O 2 :H 2 O 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.