High-resistant low-doped GaAs and AlGaAs layers are the basis to create the fast-operating high-voltage diodes, thyristors, thermosensors and so on. The difficulties while obtaining pure III-V layers by LPE are due to the presence of the background impurities in the initial charge, especially of silicon and oxygen. Significant progress has been achieved in the controlling properties of the semiconductor materials under influence of the rare-earth elements (REE) for last time. The best conditions in this aspect taking into account high chemical activity of the REE can be potentially provided by LPE. At the same time, it is rather difficult to realise possible advantages of using rare-earth elements to control properties of the GaAs and AlGaAs layers by utilising present LPE based on the adjusting the vapour phase humidity and the using quartz equipment. Main reason for that is interaction between aluminium and REE on one side, and quartz equipment on another, which prevents creation p-i-n structures in the GaAs/AlGaAs system. However just these heterostructures attract significant practical interest due to their low back-voltage currents and higher breakdown voltages in comparison to the materials with smaller energy band gap. In the present work new approaches based on the complex doping with REE and isovalent element impurities to be applied to control electrophysical properties of the LPE grown GaAs layers are developed. Influence of co-doping with Yb and Al of the gallium melts during LPE growth of the GaAs epitaxial layers on their properties is investigated. It is shown, that both the electrophysical parameters and the emitting features of deep traps of the films did get changed under influence of the doping impurities applied. Obtained results are explained by simultaneous Yb gettering action with respect to the oxygen and silicon in the solution-melt, and also by lowering the concentration of the Si in the films due to the Al entering into the Ga sub-lattice.