The authors studied nanoscale structure fabrication of multiple AlGaSb/InGaSb quantum wells. The fabrication was successfully conducted using simple resist masks for electron beam lithography and reactive ion etching (RIE) with chlorine-based gases. The etching profile after the RIE showed good vertical shape. Etching damage induced by the RIE was revealed by using photoluminescence measurements. The effects of surface recombination at the etching sidewalls were large, but the effects were suppressed by using HCl and (NH4)(2)S-x treatments. The damage was low enough to create small active optical devices, such as photonic crystals, comparably with current InGaAsP systems. (c) 2006 American Vacuum Society.