Liquid-phase epitaxy from gallium melts is generally associated with difficulties arising in obtaining epitaxial layers of n-type conductivity in the high-temperature growth range, especially using a graphite boat. One of the possibilities for purifying the epitaxial layer from background impurities and reducing the concentration of antistructural defects is using Bi-containing melt solutions. A high initial crystallization temperature is necessary to obtain a thick (50 μm and more) AlGaAs epitaxial layer. Relatively thick graded Al_xGa_1−xAs layers are used to obtain photovoltaic converters with lateral input of laser radiation, as well as in high-brightness light-emitting diodes. At an initial epitaxy temperature above 850 °C from the liquid phase in a graphite boat, intentionally undoped GaAs and AlGaAs layers change the conductivity type from n- to p-type. This paper shows that adding bismuth to the melt allows preserving the initial n-type conductivity of the grown AlGaAs layers, which simplifies the technological process of creating a photovoltaic device structure with a given doping level of the epitaxial layers. It is shown that the concentration of impurity centers decreases with an increase in the bismuth content in the gallium melt.