Hybrid Alpha Power Source

In this work, a hybrid structure is designed that combines both alpha-photovoltaic (APV) and alpha-voltaic (AV) effect. A ZnS phosphor generates photons when exposed to alpha particles. The photons are captured and converted to electron-hole pairs (EHP) in an underlying layer of InGaP PV (APV). Some of the alpha particles propagate to the InGaP directly producing EHP in InGaP (AV). Numerical simulations using SRIM compared the power output in the InGaP PV through a parametric study of phosphor thickness. The ionization energy deposited in the ZnS layer was compared to the ionization energy in the InGaP. The ZnS phosphor thickness was varied to maximize electrical power output. The ZnS phosphor also performs the function of slowing down alpha particles so those alphas that penetrate to the InGaP are less energetic and damage is reduced to the InGaP PV. Initial measurements were performed using current-voltage (IV) curves during exposure to alpha particles from a National Electrostatics Pelletron ion accelerator. The energy deposited into the phosphor and PV materials is calculated from SRIM simulations. Simulation results optimizing phosphor thickness in this hybrid APV and AV structure generates 4.3% efficient energy conversion for radioisotope battery application producing greater than 500 mu W(electrical) can be generated per 100mCi of Am-241.