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 R₀A above 4 × 10⁵ Ω cm² 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.