Wet etching and chemical polishing of InAs/GaSb superlattice photodiodes

In this paper, we studied wet chemical etching fabrication of the InAs/GaSb superlattice mesa photodiode for the mid-infrared region. The details of the wet chemical etchants used for the device process are presented. The etching solution is based on orthophosphoric acid (H3PO4), citric acid (C6H8O7) and H2O2, followed by chemical polishing with the sodium hypochlorite (NaClO) solution and protection with photoresist polymerized. The photodiode performance is evaluated by current-voltage measurements. The zero-bias resistance area product R(0)A above 4 x 10(5) Omega cm(2) at 77 K is reported. The device did not show dark current degradation at 77 K after exposition during 3 weeks to the ambient air.