Performance prediction of AlGaAs/GaAs betavoltaic cells irradiated by nickel-63 radioisotope

The performance of a n/p betavoltaic heterostructure, i.e. aluminum gallium arsenide (AlxGa1-xAs) on gallium arsenide (GaAs) substrate has been evaluated by nickel-63 (Ni63) beta-particles irradiation with anaverage kinetic energy of 17.1 keV. The thickness of AlxGa1-xAs emitter layer was set to 1.2 μm with an aluminum molar fraction of 0.1. The thickness of GaAs base region was fixed to be 3 μm. During the calculations, the reflection from the front surface, the metallurgical interface, and the limits of the depletion region were carefully taken into account. Moreover, the equivalent circuit accounts for the ohmic losses. The simulation results reveal that by using a radioactivity density of 10 mCi/cm2, the conversion efficiency (ɳ) of an optimized device structure increases up to 33%. The other cell electrical parameters, such as the short-circuit current density (Jsc), the open-circuit voltage (Voc), and the maximum electrical power density (Pmax) are observed to be 438.09 nA/cm2, 0.97 V, and 337.35 nW/cm2, respectively.