We report on the inductively coupled plasma reactive ion etching of GaInAsSb and AlGaAsSb for the fabrication of quaternary multiple interconnected module (MIM) thermophotovoltaic devices. A rapid dry etch process is described that produces smooth surfaces using BCl3 for AlGaAsSb and GaInAsSb structures capped with GaSb. Uncapped GaInAsSb was etched by adding an H-2 plasma preclean to reduce surface oxides. GaInAsSb etch rate was studied as a function of accelerating voltage, rf power, temperature, and pressure. The etch conditions found for GaInAsSb were used for AlGaAsSb etching to determine the effectiveness for isolation of the MIM cells. Etch rates of 2700 Angstrom/min with rms roughness of 0.40 nm and 3000 Angstrom/min with rms roughness of 2.33 nm were demonstrated for GaInAsSb and AlGaAsSb, respectively. (C) 2003 American Vacuum Society. [DOI: 10.1116/1.1562639].