Incorporation of beryllium (Be) and tellurium (Te) dopants in epitaxially grown Al(0.9)Ga(0.1)Asa(0.06)Sb(0.94) layers was investigated. Carrier concentrations and mobilities of the doped layers were obtained from room temperature Hall effect measurements, and dopant densities from secondary ion mass spectrometry depth profiling. An undoped Al0.3Ga0.7As cap layer and side wall passivation were used to reduce oxidation and improve accuracy in Hall effect measurements. The measurements on Be-doped samples revealed high doping efficiency and the carrier concentration varied linearly with dopant density up to the highest Be dopant density of 2.9 x 10(19) cm(-3), whereas for Te doped samples the doping efficiency was in general low and the carrier concentration saturated for Te-dopant densities above 8.0 x 10(18) cm(-3). The low doping efficiency in Te-doped Al(0.9)Gao(0.l)As(0.06)Sb(0.94) layer was studied by deep-level transient spectroscopy, revealing existence of deep trap levels and related DX-centers which explains the low doping efficiency. (C) 2017 Elsevier B.V. All rights reserved.