Power source based on Al$_{0.8}$Ga$_{0.2}$As/GaAs photovoltaic converter and YPO$_4$:Eu/($^{238}$Pu) radioluminescent emitter

An AlGaAs/GaAs photovoltaic converter for a mock-up of an environmentally friendly radioisotope energy source of ultra-long use with a YPO$_4$:Eu/($^{238}$Pu) radioluminescent emitter with an extremely low content of the isotope $^{238}$Pu $<$ 0.1 wt.% was studied. The modeling of the Al$_{0.8}$Ga$_{0.2}$As/GaAs heterostructure for the conversion of nanowatt power levels of an optical signal has been carried out. The calculated and experimental efficiency of the mock-up with a photovoltaic converter at a radioluminescent source power of 1 nW was $\sim$ 1.4%.