AbstractPraseodymium‐doped GaAs and Al0.3Ga0.7As epilayers grown on Semi‐Insulating (SI) GaAs substrates by Liquid Phase Epitaxy (LPE) were first studied in this present work. Measurement techniques, such as microscopic observation, X‐ray diffraction, Secondary Ion Mass Spectroscopy (SIMS), and Hall measurement were employed. Layers doped with Pr resulted in a mirror‐like surface, except several high Pr‐doped layers having droplet surfaces. Hall measurements reveal that the grown layers contained p‐type layers, carrier concentrations from 6.3 × 1015to 1.2 × 1016cm−3, and from 6.3 × 1015to 3.5 × 1016cm−3for Pr‐doped GaAs and Al0.3Ga0.7As epilayers, respectively. Although p‐type conduction exists, in the light of electrical features, doping of Pr into the GaAs and Al0.3Ga0.7As growth melts, is still considered to exhibit gettering properties rather than to become a new acceptor itself. Additional photoluminescence examinations were taken. Their results also indicate that Pr‐doped layers produce no new emission lines and support th