Silicon- and beryllium-doped Ga0.52In0.48P and (Al0.7Ga0.3)(0.52)In0.48P were grown by solid source molecular beam epitaxy using a valved phosphorus cracker cell. The electrical properties were investigated using van der Pauw-Hall and capacitance-voltage measurements at room temperature. The highest electron concentration obtained was 6.9 x 10(18) and 2.1 x 10(18) cm(-3) for Silicon doped Ga0.52In0.48P and (Al0.7Ga0.3)(0.52)In0.48P, respectively. The highest hole concentration obtained was 1.1 x 10(19) and 4.9 x 10(18) cm(-3) for beryllium-doped Ga0.52In0.48P and (Al0.7Ga0.3)(0.52)In0.48P, respectively. The Hall electron mobilities of Si-Ga0.52In0.48P and Si-(Al0.7Ga0.3)(0.52)In0.48P within the carrier concentration range of 10(17) < n < 10(19) cm(-3) were 940-390 and similar to100 cm(2)/V s, respectively. The Hall hole mobilities of Be-Ga0.5In0.5P and Be-(Al0.7Ga0.3)(0.5)In0.5P within the carrier concentration range of 10(18) < P < 10(19) cm(-3) were similar to 29 and similar to 14 cm(2)/V s, respectively. It was observed that saturation in both the electron and hole concentration occurred at high silicon and beryllium cell temperatures exceeding 1050degreesC and 700degreesC, respectively, which resulted from the silicon amphoteric effect. and possibly DX centers in alloy and Be precipitation-related defects. Comparison of the results from Hall and capacitance-voltage measurements gave a qualitative determination of the compensation ratio. It was also shown that the free-carrier concentrations and Hall mobility of n- or p-Ga0.52In0.48P samples are higher than those of (Al0.7Ga0.3)(0.52)In0.48P samples. (C) 2002 Elsevier Science B.V. All rights reserved.