The AlxGa1-xAs/GaAs heterostructures represent a potentially useful material for photodetectors with high efficiency in spectral range 0.4 divided by 0.9 micrometers . To produce the thermostable detectors with high radiation hardness on the base of liquid phase epitaxy (LPE) the physical and chemical foundation of such epilayers formation was developed. The abilities of LPE method wee improved due to utilization of multicomponent solution-melts with rare-earth additions. The horizontal sliding-boat step-cooled LPE technique with controlled composition of gaseous medium and additions of Yb in Bi and Ga-Bi-Al solution-melts was used as the base of technology. As a result of our investigation the quickly responsive photodiodes with improved technical, exploitative and economical parameters were produced.