Rapid and accurate threading dislocation density (TDD) characterization of direct-gap GaAsyP1-y photovoltaic materials using molten KOH defect selective etching (DSE) is demonstrated. TDDs measured using molten KOH DSE show close agreement with those from both electron beam-induced current mapping and planar view transmission electron microscopy, provided TDD < 10(7) cm(-2). H3PO4 DSE is also demonstrated as an accurate method for characterizing TDD of GaP substrates. Taken together, the DSE methods described here enable TDD characterization over large areas (> 10(5) mu m(2)) from substrate to GaAsyP1-y device layer. (C) 2014 Elsevier B.V. All rights reserved.