Simulation of GaN P+IN+ alpha-voltaic nuclear cells for stacked application

Nuclear cells made from alpha emitting radioisotope sources offer the potential of high energy density (>10 W/kg) but suffer from the effects of radiation damage, which reduces the carrier collection length. A stacked multi-junction structure offers the possibility of a longer operational lifetime by distributing electron–hole pair generation into separate unit cells. The performance of P+IN+ gallium nitride unit cells used to convert 241Am radiation is simulated using TCAD software. By varying the carrier lifetime in the intrinsic (I) region, it is possible to model the effect of the alpha particle induced radiation damage. Shortening the length of the device unit cells I-region from 10 to 0.2 μm significantly improves the charge collection. Considering different damage constants, significant gains in the operational lifetime of the cells, which make up the stack, are predicted.