Rapid 3D Defect Mapping in SiC Betavoltaics via Positron Annihilation Tomograph

Defect‐mediated recombination losses are a fundamental bottleneck for betavoltaic energy converters. Here, we introduce a rapid, nondestructive correlative approach combining positron annihilation spectroscopy (PAS) and positron emission tomography (PET) to map and quantify vacancy‐type defects and stacking faults in 3C‐ and 4H‐SiC/Si heterostructures. We demonstrate the efficacy of this approach by rapidly optimizing a thermal annealing protocol (500C, 30 min), which reduces defect density by >50% and enhances the open‐circuit voltage and short‐circuit current density of betavoltaic cells by 20% and 24%, respectively. This integrated PAS/PET methodology presents a powerful tool for the accelerated screening of materials and defect engineering in semiconductor devices and provides a foundational characterization framework for the emerging class of radioisotope‐doped semiconductors, directly addressing the self‐absorption and defect‐mediated recombination losses that currently limit the efficiency of 3C‐, 4H‐SiC:C/Si betavoltaic power sources.