GaP/Si/Ge nanoheterostructures have been obtained using the method of pulsed laser deposition, and an energy band diagram of cascade solar cells based on these heterostructures were modeled. GaP and Ge nanolayers grown on Si substrates were studied by Raman spectroscopy and X-ray diffraction. Spectral dependences of the external quantum efficiency response of GaP/Si/Ge nanoheterostructures were determined.