Luminescence enhancement effects are observed in. the plasma-etched InAS(0.45)P(0.55)/ In(0.68)Ga(0.32)AS(0.45)P(0.55) quantum wells (QWs). Characterizations of photoluminescence, atomic force microscopy, and secondary-ion mass spectroscopy reveal that surface roughening due to ion bombardment onto surface and microstructure changes resulted from Ar+ ions tunneling into the material in the plasma etching process account for the PL enhancement phenomenon. The combination of plasma etching and selective lift-off of the InP cap layer of the InAS(0.45)P(0.55)/In(0.68)Ga(0.32)AS(0.45)P(0.55) QW structures allows us to separate the two enhancement factors, which indicates the At+ ions tunneling into the crystal is the dominant factor that enhances the luminescence emission of InAS(0.45)P(0.55)/In(0.68)Ga(0.32)AS(0.45)P(0.55) quantum wells. (C) 2008 American Vacuum Society.